Resize2fs Questions
I figured I would start a new topic as none of this pertains to the previous messages I posted. I've got an almost 30-GB disk image of a working debian installation for a Raspberry pi that I should be able to easily squeeze on to a roughly 8 GB SSD card because it only takes up 10% of the 30-GB card and I think I am close but not there yet. Because I hate drudgery with regards to syntax, I wrote a little shell script that makes it easier to duplicate the same actions and also makes it easy to show exactly what is happening so far. The big image name is rpi1_good.img and it is 29 gb in size. Here are the commands that work so far. #!/bin/sh #This resets everything for a new run. sudo losetup -d /dev/loop0 #copy a backup to the image name to start fresh. sudo cp -p rpi1_good.img.bak rpi1_good.img #This takes about half an hour. Now, get to business. sudo losetup -P /dev/loop0 rpi1_good.img #This should show 2 partitions on loop0 when successful. sudo ls -l /dev/loop0* #You get /dev/loop0p1 and p2 #e2fs is required to run before one can resize. sudo e2fsck -f /dev/loop0p2 #I should be telling resize2fs to squeeze everything in to a 7GB #partition. sudo resize2fs /dev/loop0p2 +7G There are no complaints up to this point and resize appeared to work so now it is time to reduce the size of partition 2. This may be where things go off the track. I run sudo fdisk /dev/loop0 and fdisk tells me it is 29.9 GB which I expected since Partition #2 should be mostly empty but for the OS and my login directory. I note that the starting sector for P2 is 137215 since one must start at that sector and then I delete P2 and then add a new partition which defaults to 2. fdisk prompts for the first sector with a default of 2048 but I type in 137215. The last sector is in the 62-million range and I want only 7 GB as the size so I type +7G and it takes that. I then type w to save the changes and there is no complaint. The first hint of trouble is when you do fdisk -l /dev/loop0. The size count is still almost 30 GB but then a ray of Sun in that P2 has a size of around 7 GB. I outwitted Murphy this time by using another file on my computer as the target rather than the SSD card so that if it went over 8 GB, nothing annoying would happen. I watched on another console as the size climbed past 5 GB, then 6 and 7 GB and then it was up past ten so it was going to do the whole 30 GB if I hadn't stopped it. I am not sure what I missed but the manual page for resize2fs warns you to use something like fdisk to trim off the excess empty space which is what I thought I did. I would also have thought that the disk image file should have deflated like a punctured air mattress but it didn't. I think I am almost there but obviously not yet. Thanks in advance for ideas. Martin
Re: SD Memory Card (was The Raspberry Pi that Took a Day Off.)
There's always one more question that nobody mentions and none of the articles one finds on the topic don't touch. When looking at the man page for resize2fs in debian, it talks about the -b option to turn on "the 64 bit feature." __ When shrinking the size of the partition, make sure you do not make it smaller than the new size of the ext2 filesystem! The -b and -s options enable and disable the 64bit feature, respect- tively. The resize2fs program will, of course, take care of resizing the block group descriptors and moving other data blocks out of the way, as needed. It is not possible to resize the filesystem concurrent with changing the 64bit status. __ Do I need this since the Pi runs an ARM processor which would make the command #sudo resize2fs -b /dev/loop0p2 6.3g or is it the same command without the -b flag? I have determined that the 28.9 gb SSD card is 10% full with the debian installation and the files I want in my login directory. I found a 7.3 gb SSD card that has probably never been used that came with the first Raspberry Pi I bought around 2012 or so, going for a 32-gb card instead. If I shrink the Linux partition to 6.3 gb which is what the small card had available, I should have it about 40 or 50% full. I can then safely dd it on to a larger card any time I want to do so and then use resize2fs to expand the Linux partition after it is installed. What I did so far was to mount the 27-gb partition on /mnt through /dev/loop0 and edit /mnt/etc/hostname to reflect the host name for the system being rebuilt. The edit changes the image which is really neat. All that is left is to shrink it down to 6.3 gb and it should be ready to dd on to the 7.3 gb card which should be bootable on it's own but which I will use to seed a new 28-gb system that can be customized after it is running. Many of the raspbian distributions have a #1 partition that is a small fat32 lba partition for Windows users to be able to activate debian from Windows. Is this even necessary once one is using unix tools on the disk? Thanks to all the good advice from everyone. I am seeing the end of this project and have learned some new useful tricks that are good to know. Martin
Re: SD Memory Card (was The Raspberry Pi that Took a Day Off.)
My thanks to everybody who has responded here. I think the prudent thing to do is use a new SSD card and I have one that is supposed to be a full 32 gb. The card I was able to finally clear the partitions on is several years old but I think it is still good but the suggestion to use it in a less mission critical application is a good idea plus it is not a full 32 gb. I have a radio receiver that can store information on one of these cards and I'll use it for that since if there turns out to be a bad cell somewhere, the world won't end like it can if one's kernel or sector information becomes corrupted if it happens to land in a vital piece of code. Again, many thanks. Martin McCormick
Re: SSD Memory Card (was The Raspberry Pi that Took a Day Off.)
David Wright writes: > I've not heard of that problem. You were prevented from zeroing the > entire device, which would have wiped the partition table anyway. > > What I would want to check is that the OS isn't doing something > stupid, like trying to automount it, failing, and consequently > setting the device readonly. By OS, I really mean DEs, or > automounters in general. > > You could also try zeroing it in another machine, ± any adapters > required. (Bear in mind that adapters do have readonly sliders.) I suspect this is the crux of the problem. the adapter I connected is a card reader. You put the SSD in a little plastic jacket that holds the SSD in such a way that the card reader can access the edge connector but the holder jacket has no electronics. There is a small notch in the plastic of the jacket on the left edge and the right front corner of the plastic carrier has a diagonal cut to prevent someone from putting it in upsidedown. Since I posted, there is good news but I still wonder if I am not going bonkers because after unplugging the Sony card reader and plugging it back in, I now am getting device /dev/sdg instead of /dev/sdh. I was also able to do the following: #sudo fdisk /dev/sdg which gave me the fdisk utility as before so I did what crazy people do which is to do the same thing as before, hoping for different results. By Joe, I got them. I typed d to delete a partition and it put partition 2 up as the default candidate as before so I selected it and then typed d again which told me that only partition 1 was left so it was deleted. I had gotten this far before so wasn't too excited but type w and this time got the message stating that the partition table had been rewritten and fdisk then exited. Now, doing sudo fdisk -l /dev/sdg yields 1wb5agz martin tmp $ sudo fdisk -l /dev/sdg Disk /dev/sdg: 28.8 GiB, 30908350464 bytes, 60367872 sectors Disk model: USB HS-SD Card Units: sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disklabel type: dos Disk identifier: 0x680226ff The partitions are gone. My latest screwball theory is that the Sony card reader went in to some sort of protective mode after the dd operation overwrote the device. My unplugging the reader and plugging it back in reran the driver which reset the protective mode back to normal which may be why it all worked right this time. One last question: Since the image will still be too large as it is, can tunefs be run on it or a copy of it to shrink about 4 gb of user space? The good system I copied the image from only had about 12% of the partition used so I should be able to transplant it to the smaller disk if tunefs can do that and still leave a bootable device. Thanks for all useful ideas. Martin McCormick
Re: SSD Memory Card (was The Raspberry Pi that Took a Day Off.)
Bijan Soleymani writes: > Can you delete both partitions, create a new single linux partition, > reboot > then run mkfs.ext4 to create a single new partition and then just install > linux onto it or try dd again? Great suggestions but I can't. Part of the typescript output I included was me doing just that and I was root when I did it but the squawk is that I don't have permission as if I wasn't root. If writing to the SSD card was possible, I could have just done the dd command, only with a smaller input image and it would have worked. Thank you because what you suggest would be the normal way out. Martin Martin
Re: SSD Memory Card (was The Raspberry Pi that Took a Day Off.)
Charles Curley writes: > I'm no expert on RPis, but that sounds to me like the SD card is > protected against writes. Check for any physical write protection > switches on the card itself and the holder. Thanks for the suggestion, but this is one of those SSD cards that often is found in a camera and resembles a wafer the size of a thumbnail. It has a projection that acts as a key way to keep a user from inserting it in the wrong way and there is a groove for a fingernail to help pull the chip out of the socket. This particular one was reading and writing just fine until I bricked it by the DD that must have overwritten some address which now makes it unwritable. It went from good to bad without my removing it from the card reader so there should be some way to at least clear it for writing again. Apparently, it stops being writable if the partition table is corrupted. In my case, I just want to delete both partitions and start over. The OS is debian Buster and has all the tools you can expect to find and runs on a 64-bit ARM. Otherwise, it's pure debian Linux. Martin
SSD Memory Card (was The Raspberry Pi that Took a Day Off.)
I thanked the person who responded to my post and reported that there were no unusual log entries in syslog on the failing system so not much to go on. I decided to upgrade the Raspberry Pi which was suddenly having this mysterious problem as I have backups of the failing system so I figured I'd just clone a buster image from another Raspberry Pi that is running buster and use dd to copy it to the Raspberry Pi which was running stretch and having that weird problem. Then, assuming the upgraded Pi was alive, I could use the backup from the stretch system to put all the user space from my old home directory on the new buster system but I messed up again. The SSD card from the older system is 28 GB and the working buster system's SSD card is 32 GB so the smaller card filled up and I achieved that "no space left on device" state that we all love to see. Simple, I thought. I'll just delete all partitions, and do the dd if=rpi_good.img of=/dev/sdh which is where this card shows up when it is in the reader and I can maybe dd a smaller 8.5-gb drive which I have that has almost never been used. Murphy has struck again. Here is what happens when I try to use that 28-gb SSD card: Script dump follows Script started on 2022-01-26 20:03:52-06:00 [TERM="Linux" TTY="/dev/pts/3" COLUMNS="80" LINES="25"] 1wb5agz martin tmp $ sudo su - [sudo] password for martin: root@wb5agz:~# fdisk -l /dev/sdh /dev/sdh: 28.8 GiB, 30908350464 bytes, 60367872 sectors Disk model: USB HS-SD Card Units: sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disklabel type: dos Disk identifier: 0x680226ff Device[0m [1mBoot[0m [1m Start[0m [1m End[0m [1m Sectors[0m [1m Size[0m [1mId[0m [1mType[0m /dev/sdh1 8192 137215 129024 63M c W95 FAT32 (LBA) /dev/sdh2 137216 62333951 62196736 29.7G 83 Linux root@wb5agz:~# fdisk /dev/sdh Welcome to fdisk (util-linux 2.33.1). Changes will remain in memory only, until you decide to write them. Be careful before using the write command. Command (m for help): p Disk /dev/sdh: 28.8 GiB, 30908350464 bytes, 60367872 sectors Disk model: USB HS-SD Card Units: sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disklabel type: dos Disk identifier: 0x680226ff /dev/sdh1 8192 137215 129024 63M c W95 FAT32 (LBA) /dev/sdh2 137216 62333951 62196736 29.7G 83 Linux Command (m for help): d Partition number (1,2, default 2): Partition 2 has been deleted. Command (m for help): d Selected partition 1 Partition 1 has been deleted. Command (m for help): w fdisk: failed to write disklabel: Operation not permitted root@wb5agz:~# logout 2wb5agz martin tmp $ exit Script done on 2022-01-26 20:07:59-06:00 [COMMAND_EXIT_CODE="1"] So close and yet so far away. If I try to use dd on /dev/sdh again, I get: 1wb5agz martin tmp $ sudo dd if=~/rpi/rpi2_good.img of=/dev/sdh [sudo] password for martin: dd: writing to '/dev/sdh': Operation not permitted 1+0 records in 0+0 records out 0 bytes copied, 0.021666 s, 0.0 kB/s 2wb5agz martin tmp $ exit I've had usb thumb drives fail when filled to capacity and, if I hadn't been tired, I would have noticed that the image was 4 gb too large so this wouldn't have happened but surely, there is some way to at least zero out everything so the SSD can be either reformatted or used as the output of an image transfer using dd. The SSD passed a fsck test earlier in the day before I blew it up so the chip should be salvageable. I don't care for recovering either of the two partitions which will be overwritten anyway if the SSD can be made writable again. One can mount /dev/sdh1 which is the fat32 partition but it mounts as read-only. If you try /dev/sdh2, you get a squawk that says that this partition is not in /etc/fstab which is certainly true but it doesn't mount either so mount doesn't understand what I was trying to do. This is the partition that got the overflow condition so it's utterly useless. These last 2 days, I have been a day late, a Dollar short and 1 step behind on what shouldn't be really that big of a problem. Martin WB5AGZ
The Raspberry Pi that Took a Day Off.
This Pi is running Debian Stretch. I believe that's what version 9 is called. I have it capturing audio from a radio receiver and it's been doing that for several years now and it was doing that yesterday morning. Later in the day, I downloaded more audio and, after a long pause, I got the message from ssh that the Raspberry Pi wasn't there any longer so I retrieved the Pi from the room where it was and brought it to my Debian desktop system to work on it. I could login to the Pi which seemed to be up and running but the short story is that it couldn't talk to any address but our router.I couldn't even ping it's interface from the Pi, itself. If I was on the Raspberry Pi's console, everything looked normal as long as one wasn't using the TCP/IP interface. You could even do a ip addr or an ipconfig -a command and it would show that it had gotten the correct address from our dhcp server which is in the router. It would successfully ping the router but no other addresses, not even the address it uses on our network. I finally quit messing with it and went to bed but fired it up again today, January 25 and low and behold, it just came right up and is now back doing what it has been doing. Is it possible that it got a corrupted lease for dhcp from the router? Dhcp leases on our Netgear router are issued for not quite 24 hours so it may have gotten a bad lease, kept renewing it for the time it was powered up and then it got a new version of that lease today and all is well. It's the same IP address because I have put it in the router as a static IP address. The other thing that is weird is that the Raspberry Pi in question has both a wired Ethernet and a WiFi interface and both were misbehaving identically. Normally, the wired port is not used and the dhcp lease renewal process happens over WiFi. The results of ip addr always showed a correct subnet mask and the only rules in iptables are the 2 default rules. In other words, all looked normal except that it didn't work. While I had it on the work bench, so to speak, I ran fsck -fy on the SSD card since it has been a couple of years since I last did that and there was not a single squawk about anything. Thanks for any ideas about how things got wrong and then magically fixed themselves. When I turned it off last night, I gave it the halt -p command. The power supply has no switch so I unplugged it from power so it started fresh about 8 hours later. Martin WB5AGZ
Re: /usr/share/calendar.usholiday
deloptes writes: > And if you look into the file, you see it has no years associated with the > date, so it doesn't matter when it was written unless there was a change > in > the official holidays in the US. Correct. I see two types of date references, exact dates such as Christmas and New-year's and rule-based dates which are some designated day such as the second Monday in a given month, what the British refer to as a "bank holiday." My original question about this file has been answered in a round-about way in that there are also two types of holidays. St. Valentines day, for example, is not a postal or bank holiday but one will certainly get in deep trouble on the home or romantic front if that day is forgotten. Also days like Arbor Day are a nice idea but nothing about normal commerce or daily activities changes I also noticed that today in the United States should be marked but hasn't been yet. It is the third Monday in January which, since 1986 has been the official recognition of the birthday of a US civil rights leader, Martin Luther King Jr. The entry in that file probably should read: 01/MonThird Martin Luther King Birthday (3rd Monday of January) It is now a major holiday and schools and government offices are usually closed so it should probably be there. Thanks to all and sorry if I created any confusion about the path. Martin McCormick.
Re: /usr/share/calendar.usholiday
Greg Wooledge writes: > On Sun, Jan 16, 2022 at 09:58:11PM -0600, Martin McCormick wrote: > > There's a stale version of this file on my system that reflects > > when Debian was installed but it brings a question to mind. > > The one in the Subject: header? Are you sure that's the correct > path for this file? I goofed. I thought I could remember it long enough but it is actually /usr/share/calendar/calendar.usholiday I also still had an old directory tree from when I had wheezy on the system and there is /home/wheezy/usr/share/calendar/calendar.usholiday > > On Debian 11, I have the file /usr/share/calendar/calendar.usholiday I am presently running Debian GNU/Linux 10 as in Buster. --- > which is a different path from the one you showed. That was just a mistake on my part. Sorry to add more confusion. This also reminds me to get rid of the old wheezy files since I now don't even remember why I saved them but they are getting backed up nightly for no reason at all other than they get caught up in the sweep. Martin
/usr/share/calendar.usholiday
There's a stale version of this file on my system that reflects when Debian was installed but it brings a question to mind. Does this file simply cause messages to appear on an event calendar or can it be used along with crontab in some way to either cause or prevent cron jobs from running if a date matches one of the dates in the file? I use cron and at jobs all the time and have thought that it would be nice to skip some jobs if the day is a holiday and the result might be not what one wanted. Right now, I don't think this file is doing a thing as it is for 2017 but this is why I am asking. I also saw versions of that file for other countries such as the UK. Thanks for all good responses. Martin McCormick
Curious Question about an Extra MAC Address
I was inventorying all the systems on our WiFi and wired network so I did the following: sudo nmap -sn 192.168.1.0/24 followed by sudo arp -a and I found nothing extraordinary so I also got on our Netgear router and told it to cough up a list of attached devices, showing the same list of stuff that the first two sweeps found. Additionally, there was 1 mac address with no other information such as an IP address or system name, just that MAC on a row all by itself. I had been looking for our DVD player which has the ability to view streamed movies and I think this might be it. As a computer user who is blind, I don't directly use this player but my wife does. We usually play DVD's from it however she did use it once to watch a movie off the network and it worked fine. I asked her if she remembered giving our WiFi password and she said no but was given a message to go to a certain url to authorize payment in order to watch the film and it all worked down to the monetary slurp so this is not a complaint or gripe about anything. My question is, did the link she went to on the computer or maybe her iPhone use javascript to get our WiFi password and if so, how did the player get the authorization to use our WiFi? The stray MAC showing up on the router is probably the player broadcasting an attempt to get in the network but to do so, it has to send the password in order to get a DHCP lease which would then allow it to get on the internet. I am just curious about how did this work and could a person cause it to log on to our WiFi network and receive a video stored on a system here? I'm not trying to rip anybody off but it's good to know what extra features are under the hood. What I am actually thinking of is more like a DVR where a computer can record a TV show like the old-school VCR's and then one could play it back through the DVD player on the network. This player can also update it's firmware when necessary and we've never been prompted from it for a WiFi password. It just seems to be able to get through when it needs to. I guess this could also be a neighbor trying to mooch WiFi, but I doubt it. Everything with an IP address belongs to us and there are no odd amounts of data coarsing through our router that aren't caused by us. This is a neighborhood in a college town so one must be careful but not too paranoid. Thanks for any good ideas. Martin
Re: eMail Com Between Hosts on a Private Net
One more question I should know the answer to but am not sure of. The debian Buster system I use for email presently uses fetchmail to get mail from the ISP and is configured to use that ISP's smarthost for out-going mail. I do not want to effect (= muck this up) this functionality because it works well for now. Shouldn't I be able to install an imap server on the debian box and forward messages of interest to it, then reach imap4 on the private net from any system that speaks imap or has an imap client? That would do what I need to do. When I was researching, the article in wikipedia I read said that many commercial systems have email clients which understand imap, pop3, etc. The systems likely to do this on our network are a windows10 box, an iMac and maybe an iPad. The idea would be to forward an email message needing this attention to imap on the linux box, contact the Linux box from one of the devices I mentioned, and download the message at which point it would e as if that system had been hooked up to the ISP and received it. I was all ready to use .local as our domain name and then I looked that up and there is a good wikipedia article which explains how that is problematic and recommends using something like .lan, .office or something else that isn't likely to be registered as a top-level resolvable domain name. The machine I receive email on presently would be a good candidate for running a mdns but our netgear router advertises whatever dns's the isp uses for obvious reasons and that's fine but it would be nice if the mdns's address could also be known to clients on our network which could make DNS queries to each other's names that would resolve properly. Is there a way to advertise the mdns so that the router picks it up but doesn't drop the internet DNS's that we all need to resolve the rest of the world? I do remember when I was working, we explored open-source network authentication systems which involved fake DNS's that one had to advertise as such so their information wouldn't corrupt the proper working DNS's which could really mess things up if somebody happened to pickup and cache the wild card * that sent all new supplicants to the authentication server after they were already up and running. In our case, the corruption would be okay and done for good reasons but the dhcp server in our router already advertises two domain name servers so ours would have to be learned about by discovery. Thanks again. Martin McCormick
Re: eMail Com Between Hosts on a Private Net
Joe writes: > Indeed so, it is even in a folder called 'etc', which I think is in a > 'drivers' folder. It's a while since I used it. There may be an > existing default or example \etc\hosts file. The LMHosts file is also > here, but of interest only to Windows networks for speeding up share > lookups. > > -- > Joe My thanks to all who replied and thanks for reminding me of some of the considerations one needs to think of when setting this all up since that's what I used to do as part of my job before retiring in 2015. As for there being 16 subnets in the 192.168.x.x number space, one can use variable-width subnet masks so unless you have a lot of hosts or, for some reason, are sharing space with another subnet, one can spread out to a Class B-style network which would be the whole space and have a subnet mask of 255.255.0.0 or you can make lots of little subnets of various mask sizes with blocks of 16 addresses being about the smallest subnet that is practical. Remember you always lose the all-zeros and all-ones broadcast addresses because they are special plus there is likely a router address taken by the router which leaves 13 addresses for hosts in each subnet. I remember early in the nineties our campus went from a single Class C to a Class B network and the whole campus used the Class B subnet mask with bridges holding the whole thing together. You should have seen some of the arp storms that would blow up like wild fire when somebody had a misconfigured host trying to be helpful or maybe deliberately misconfigured because somebody got their socks in a wad over something and started the fire on purpose. It wasn't long before we began more efficiently using the number space with big departments getting let's say 1024 or 512 possible addresses and others getting 16 or 32 addresses. By the time I left, we were using the huge private network space of 10.0.0.0 with aNAT or Network Address Translation to parts of the old Class B network and it generally worked well. I wrote a C then a perl program which would assign IP addresses for hosts on our networks that knew the sizes of all the subnet masks so assigning IP addresses was something anybody in our group could do without much more information other than what host name the customer wanted and what building it was in. My job was basically to encode all that in to rules for automation to keep us safe from making mistakes and it worked. Martin
eMail Com Between Hosts on a Private Net
The installation, here, is like millions of others. We are on a private VLAN with the router acting as the gateway to our ISP's network and the internet. There is nothing unusual about that so the question is Can systems on a 192.168.x VLAN use smtp to send mail to each other? I really should know the answer to this because I am a retired systems engineer who used unix systems and mailers all the time but that was in a university network and I would just assign a DNS name to each box and maybe a MX record if it was necessary so that box1.midlevel.edu could deliver mail to box2.midlevel.edu whether it was across the room or on another continent. The DNS support is what you don't have on a private VLAN so I want to do this in a safe but simple way. This would make it possible for Linux boxes on the network to send messages to the system I normally receive mail on so that squawks about a process crashing or some other problem are sure to be seen. The other systems sending those messages don't even necessarily need to send mail outside the network but they do need to send mail to the system I normally read mail on. I looked up this topic using duckduckgo and found very little hits that were on topic and lots of mercantile buzz about email hosting companies, etc. All are necessary but not what I was asking about. I have put static IP records in to the dhcp server on our router so 192.168.1.xx will always either have a specific host at that address or nothing if the MAC address changes and the record hasn't been updated. Also, I have put /etc/hosts files on Linux systems and a Mac and I believe there is a hosts file one can add to Windows systems for a similar effect. Thanks for any good ideas. Martin McCormick
Re: Proprietary USB Drivers; Ya Gotta' Love'em.
So, what is the easiest route to end up with a kernel that has this patch in it? The image for the current kernel is 4.19.0-5-686-pae The Raspberry Pi is an arm-based system and the image version number is probably different but the idea is the same, have a kernel that doesn't choke when one is using the ICR-30 usbC port. To put it bluntly, this is an area of Linux I have very little familiarity with because generally, Linux kernels just work so this is a left-handed complement in that I think this is the first kernel bug that I have encountered ever. I am sure I have run kernels with other bugs that I didn't know about but this is the first time one has bitten me, so to speak. Thanks. Martin WB5AGZ Martin McCormick WB5AGZ
Re: Proprietary USB Drivers; Ya Gotta' Love'em.
Gene Heskett writes: > You forgot to mention it can get the message thru better because it has a > 12 db advantage over competing noise compared to the original AM, > sometimes called Ancient Mary in our circles. I did forget that but you are correct. another interesting thing about ssb which includes both sidebands is that it was first tried during the 1930's as a concept and had to wait until after World War II before amateur radio operators, the millitary and commercial folks began using it routinely. To not stray too far from the group purpose, the usb dongles that give you a wide coverage receiver from 26 to almost 1000 MHZ use basically math to decode sideband, AM, FM and data using DSP techniques. Martin
Re: Proprietary USB Drivers; Ya Gotta' Love'em.
Charles Curley writes: > Possibly a known kernel bug. > > https://forums.opensuse.org/showthread.php/538695-USB-driver-Zero-Length-Descriptor > > https://lore.kernel.org/lkml/1507709452-31260-1-git-send-email-msa...@iotecha.com/ > > -- > Does anybody read signatures any more? > > https://charlescurley.com > https://charlescurley.com/blog/ Thank you. That's got to be it. I've been doing debian Linux since right around 2000 but I must admit that I don't know the easiest way to include the patch referenced in the second link. I will need to do that on an i86 box plus the Raspberry Pi I first discovered the issue on since I am apt to have the radio connected to either system and, if this problem is fixable, this solution is preferable because the radio defaults to using the usbC port as the serial port so it should still work if a full reset is ever needed and the mechanism for usb should naturally accept as many different devices as practical because you never know what you will need to connect until you try it and it fails. As an amusing aside, the radio has a usb mode, but that's totally unrelated because in that case, USB stands for upper side band and is a very energy-efficient method of radio communication because it is only a spectrum of frequencies consisting of the sidebands of an audio signal without the carrier. It can be LSB or lower side band or USB for upper side band. Nothing like a few new acronyms for your day. I guess that's TMI. Martin McCormick WB5AGZ
Proprietary USB Drivers; Ya Gotta' Love'em.
This is an embedded usb serial port in a radio receiver which works in MS Windows10 and I was hoping to write some control routines for a Raspberry Pi running buster and it does the following: Sep 22 20:17:15 rpi2 kernel: [551843.541477] usb 1-1.2: new full-speed USB device number 6 using dwc_otg Sep 22 20:17:16 rpi2 kernel: [551843.674681] usb 1-1.2: not running at top speed; connect to a high speed hub Sep 22 20:17:16 rpi2 kernel: [551843.684432] usb 1-1.2: New USB device found, idVendor=0c26, idProduct=002b Sep 22 20:17:16 rpi2 kernel: [551843.68] usb 1-1.2: New USB device strings: Mfr=1, Product=2, SerialNumber=3 Sep 22 20:17:16 rpi2 kernel: [551843.684452] usb 1-1.2: Product: IC-R30 Sep 22 20:17:16 rpi2 kernel: [551843.684460] usb 1-1.2: Manufacturer: Icom Inc. Sep 22 20:17:16 rpi2 kernel: [551843.684468] usb 1-1.2: SerialNumber: IC-R30 16002557 Sep 22 20:17:16 rpi2 kernel: [551843.727911] cdc_acm 1-1.2:1.0: Zero length descriptor references Sep 22 20:17:16 rpi2 kernel: [551843.727940] cdc_acm: probe of 1-1.2:1.0 failed with error -22 Sep 22 20:17:16 rpi2 kernel: [551843.728056] usbcore: registered new interface driver cdc_acm Sep 22 20:17:16 rpi2 kernel: [551843.728061] cdc_acm: USB Abstract Control Model driver for USB modems and ISDN adapters Sep 22 20:21:11 rpi2 kernel: [552078.765119] usb 1-1.2: USB disconnect, device number 6 So much for that. There is one other possibility. It is possible that one can go to one of the menu options and flip a virtual switch that will take the serial data that should have been on /dev/ttyACMx and put them on a logic-level serial line that is accessible through the right stereo channel of a 3-conductor jack. Whether or not that works is beyond the scope of this list so my question is whether or not there is a wrapper program of some kind in Linux that can fool an application like the serial port module that tried to run here in to thinking that it is home and among friends when it's really been kidnapped. The possible use of a logic-level serial line is probably what I will need to do but that means that if one resets the radio to factory defaults, one will have to go in to the menus on the radio's screen and restore the virtual switch setting. As a computer user who happens to be blind, that's a major pain as well as in a case where the radio is remotely located and one is operating it headlessly. I smiled a bit when reading the syslog admonition to connect to a high-speed hub. That would be quite a trick. Thanks for any constructive suggestions. Martin McCormick WB5AGZ
Re: Swiss Army Knife of Sound has me Baffled.
Dan Ritter writes:
> > arecord: set_params:1345: Channels count non available
> > sox FAIL formats: can't open input `-': WAVE: RIFF header not found
>
> Keep recording 2 channels. Your hardware doesn't like it
> otherwise.
>
> You can ask sox:
>
> sox -t wav -c1 - -r44100 $filename
>
> to merge the channels to a single output channel
>
> I believe, but have not tested, that a final argument to sox of
>
> remix 1
>
> will get you just the left channel, or remix 2 for the right
> channel.
>
> -dsr-
I haven't tried anything new yet but that sure looks right and
will probably work.
Thanks to all who responded. This is what I like about
this list as it presently exists. I had figured out that the
problem was with the hardware which is a fairly decent device
but severely limited in Linux because a lot of it's power comes
from a proprietary driver like a number of other devices such as
winmodems, etc. Then I read this:
Nicolas George writes:
> If you read carefully, you will notice that your problem is not with
> sox, it is with arecord: sox only fails because arecord fails and does
> not produce anything.
>
> arecord itself fails because "channels count not available": the sound
> device you are using does not like mono, it obviously like only stereo.
>
> You have two options:
>
> - Use a sound device that supports mono. Since you cannot change your
> hardware, it needs to be done in software with an ALSA plugin. This is
> all streamlined, you only need to write plughw instead of hw.
>
> - Keep recording in stereo, and have sox convert it to mono before
> saving. You will need to peruse the manual page of sox to know the
> option, I only ever use ffmpeg for obvious reasons.
>
> Note that:
>
> - If you use plughw instead of hw, then the ALSA plugin can also
> resample, and therefore you no longer needs sox at all.
>
> - sox is capable of recording from ALSA directly, with something like
> "-t alsa plughw:0".
>
> Regards,
I actually did get a message from arecord about using a plugin
and you have answered the question as to what needs to be done
to make that happen. I had not even thought of the plugin
solution so this is a whole new possible route to success which I didn't even
think of before.
David Wright also writes:
> Try -r 8000, or leave out -r and -c entirely, and you should
> succeed. But I doubt that's really your priority, is it?
>
> > […] and I
> > guess I could leave it in stereo mode and tell sox to mix the
> > left and right channels which is fine with me but kind of clunky.
>
> That's why it's the "Swiss Army knife". After mixing the two channels,
> you can write to a single-channel WAV file.
>
> What you can't do is tell /arecord/ to use an ADC that doesn't exist.
>
> Cheers,
> David.
I am in no great hurry so I will probably try both the
plugin solution and the sox coding and save them both for later
as the idea is to end up with something that is both efficient and
useful.
Thanks, everybody.
Martin McCormick WB5AGZ
Swiss Army Knife of Sound has me Baffled.
I have a little shell script called fullstereo which works fine. It's short so I'll show it to you. It records sound from a Creative Labs usb sound card which is probably much happier on a Windows box but that's not where I need it. It has only 1 sampling rate that works under debian and that is 48 KHZ. I want 44.1 KHZ and I get 2 good stereo channels with the following script: #! /bin/sh cd ~/tmp filename=$1.wav echo $filename arecord -D hw:1,0 -r 48000 -d $2 -c 2 -f S16_LE - \ | sox -t wav - -r44100 $filename $2 is a value in seconds, minutes or hours and it goes like a house on fire with no problem. So, I want a mono version. Let's try this: #! /bin/sh cd ~/tmp filename=$1.wav echo $filename arecord -D hw:1,0 -r 48000 -d $2 -c 1 -f S16_LE - \ | sox -t wav - -r44100 $filename This hasn't worked yet. It is identical to the good version but for c 1 as the number of channels to arecord instead of c 2 . When running that script, this is what happens: $ ./highmono testsound 30 testsound.wav Recording WAVE '-' : Signed 16 bit Little Endian, Rate 48000 Hz, Mono #Good so far and then arecord: set_params:1345: Channels count non available sox FAIL formats: can't open input `-': WAVE: RIFF header not found Darn! A couple of microseconds before that, the same process understood what I asked it to do. When the -c parameter was set to 2, it understood what to do with the standard output but with c set to 1, it did what you see above. I can't seem to figure out why 1 channel output is any different from 2 channel except that the wav header should be pretty much the same with a channel count of 1 instead of 2. The man page for arecord even says the following: -c, --channels=# The number of channels. The default is one channel. Valid val‐ ues are 1 through 32. Theoretically, one could leave out -c 1 and it should go ahead as if that flag was actually there but it breaks instead. This might also be because one can not set any parameters without the Windows driver and I guess I could leave it in stereo mode and tell sox to mix the left and right channels which is fine with me but kind of clunky. I am asking the list's wisdom in case there is a better way to produce the mono channel. Thanks. Martin WB5AGZ
Grub Success at Last
I did it! It works! Okay. Here's the short story. I read some more stuff about building a boot drive for another system than the one being used for the rescue. In this thread were the usual tales of woe which I have also experienced when misusing grub such as "Oh #%^*! Now I've got 2 systems that won't boot." a poster on that thread states: I'm not a grub2 expert (sorry) but try adding --skip-fs-probe to your grub-install line, I have found this prevents creation of /boot/grub/device.map which can cause booting to a grub prompt. I think that without this parameter grub-install, instead of doing what you tell it, thinks it is cleverer than you, and may do something different. Another thing is to be sure you are using the right grub-install (i.e. for grub2 and not for original grub). This isn't a problem if you are inside Centos but with SystemRecoveryCD both versions are available and so you have to use grub2-install. I learned the hard way... And as @wurtel pointed out (kudos), you should specify a drive not a partition. Grub2 installs in sector 0 of the whole disk drive, and this 'stub' is what runs at boot time, but it needs to know whereabouts on the disk it should install the files for the next stage of booting - this is what the --root-directory parameter is for. (I think.) Reading man grub-install and googling I see that --root-directory is not really meant to be used for grub2 versions 1.99++, though it does work in my experience. You are meant to use --boot-directory and refer to the actual boot directory, so this would give you: grub-install /dev/sdb --skip-fs-probe --boot-directory=/media/new_drive/boot End of quote I did the following: #!/bin/sh #mount the drive being repaired. Uncomment lines as needed. sudo mount /dev/sdd1 /mnt cd /mnt/boot #installing to the mounted disk sudo grub-install \ --skip-fs-probe \ --boot-directory=/mnt/boot/ /dev/sdd When you boot your disk that starts out on /dev/sda1, it's the first partition, in this case, so it will be /dev/sda1 not /dev/sdd1 . This was quite a long thread and people were remarking on how it is easy to get confused and do the wrong thing. Anyway, It booted right up and then I discovered there was no network. The network issue was only tangentially related because the update-upgrade process also install some more strict and modified ethernet interface naming rules and eth2 just doesn't cut it any more. Now, it's enp0s17 on the system that just got revived and enp0s18 or something similar on the system that got the same upgrades but is a little newer and took the tharapy much easier. Everything's working again at least in the Linux world. I saw this ad on TV for some product that is supposed to improve brain function and memory but I can never remember it's name. I could use a few more IQ points and things would flow a little faster around here. Thanks for all the help, everybody. Martin
Re: A Grub Boot Question about initrd
Felix Miata writes: > This is a big lurking booby trap that could have been the problem both > last time > and this time. It's one of the reasons why installation systems and Grub > switched > from using device names to using UUIDs: inconsistent and/or unpredicable > device > enumeration. > > Is this a PC with both PATA and SATA controllers? These old PCs can > compound the > issue. > > Different kernel, disk controller, USB controller and BIOS combinations > can cause > e.g. an SATA or PATA disk sda to become sde, or sdb become sda, IOW, > device names > that don't persist. UUIDs are supposed to prevent inconsistent device > names from > being a problem, but in a rescue environment, it can muddy the waters, or > backfire. Yes on all counts. These are old PC's that use IDE controllers. The IDE cables end in the normal 34-conductor header with one pin missing on one side that plugs directly in to the drive. In this case, the connector plugs in to a SATA-to-IDE converter with a female SATA connector. I believe you have hit the nail on the head because I know for a fact that the devices change names. On the working system, the boot device we would normally think of as /dev/sda is /dev/sdc and 5 minutes from now might be /dev/sdq depending on what drives were plugged in to usb ports when the system booted. Just yesterday, I mounted /dev/sdd, thinking it was the now infamous unbootable drive and immediately realized that I was looking at the boot drive that starts the good system. I had plugged a thumb drive in to a usb port some time earlier and then rebooted the system while failing to remove the thumb drive as it wasn't even being used right then. Let's see. $ dd if=/dev/sdd of=/dev/sde What could possibly go wrong? Just kidding this time but that's what we are dealing with. That possibly lethal command can work but only under the right circumstances so if one forgot to recreate the world one was working with, it's tuition in the school of hard knocks. I haven't yet totally given up and done anything else rash so it's still full steam ahead. This is one of those situations where if a person has the time, this can be a teachable moment. I've got several thumb drives that I mount based on their UUID and that method of doing things is your friend if you understand how to use it. If not, what one ends up with is total chaos. Felix's message hasn't saved the day yet but it confirms my hunch that the UUID's have been at the heart of this problem all along because there is simply no other logical reason why one can not transplant the same boot logic from one system to the other when they are functional copies of each other. The trick will be to replace every UUID personalization which is doable. Whether it is practical still remains to be seen. To briefly reference an earlier message, I checked the good system to see what rsnapshot did over night and /boot is now committed to a series of little capacitors which is how SSD's remember things. From fstab: # /etc/fstab: static file system information. UUID="49c4eda8-3bcc-445e-841b-513b07d560fe" /var/cache/rsnapshot ext4 relatime,rw,user,noauto 0 0 If that drive wasn't always plugged in, the boot drive would have a different device number than /dev/sdc1 which is also mounted by UUID. That drive also plugs directly in to a usb slot and not any extender to hopefully insure that it is more likely to be present. I will uncompress the initrd files and see how hard it will be to find the UUID and change it to what it should be on the problem target system. Again, thanks to all. Martin WB5AGZ
Re: A Grub Boot Question about initrd
I admit I made several big mistakes, here. The first was not having a backup of /boot as I thought I did. The next is thinking I could just copy the whole boot directory from a known working system and be able to get it to work by using sed to replace the UUID's of the system it was on with those of the system it will be on. Had I backed up the broken system instead the minute I knew there was a problem, it would have been fixable. Trying to transplant the good boot system to a different machine really should work if one knows what all changed but if that was the case, I'd be crowing about how I got it working. I may try one last thing which is to decompress the initrd files and see if there is a way to make sure they work after transplantation. At this point, it's probably more important to know what is poisoning the well as a training exercise since having good backups of /boot would have turned a major halt in to a minor irritation. Trust me. The good system is going to get daily backups of boot and grub every 24 hours from this day on. I haven't actually done anything yet to clone the good system's boot drive because I want to do the clone in the middle of the night when things are quieter and I don't run fetchmail in the wee hours so the backup sees a more stable file system. If, by chance, I end up actually making the broken system work, I'll let you know what it was and the one drive can serve the whole system again. Martin
Re: A Grub Boot Question about initrd
Felix Miata writes: > IMO you gave up too soon. IIRC you never showed us output from parted -l > or fdisk > -l. Very likely on the problem PC the / filesystem was/is not on the first > partition, where often lies a swap partition. Very likely root=/dev/sda2 > would > have been/be correct. Sorry. I meant to do that. Swap is the last partition. Disk /dev/sde: 29.8 GiB, 32017047552 bytes, 62533296 sectors Disk model: 600 Units: sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disklabel type: dos Disk identifier: 0x0080 Device BootStart End Sectors Size Id Type /dev/sde1 2048 59314876 59312829 28.3G 83 Linux /dev/sde2 59314877 62533295 3218419 1.5G 5 Extended /dev/sde5 59316925 62533295 3216371 1.5G 82 Linux swap / Solaris $ ls -1 /mnt/ bin boot dev etc home initrd.img initrd.img.old lib lost+found media mnt opt proc root run sbin srv sys tmp usr var vmlinuz vmlinuz.old
Re: A Grub Boot Question about initrd
Thanks to all for the advice and knowledge you shared about how grub works. I am writing this on June 6 and early this morning, I edited the boot command in the grub shell after verifying that my stubborn no-boot drive truly was sitting at hd0,1msdos and grub-install had picked out hd2,1msdos for every single drive reference, even the bare metal one. I did try that one first in case I was missing some magic but the only drive on the whole system was that one and listing the contents of (hd0,1msdos) show exactly what you see if looking at / so grub showed it exactly where one would expect it to be and hd2,msdos is pure science fiction on that system so I set every drive reference to hd0,1msdos except the root which grub wanted to set to /dev/sdc1. The sample that Greg Wooledge showed looked very close to how my grub.cfg looked after doctoring the drive references to point to hd0,1msdos. and I tried booting that way and set the root parameter to /dev/sda1, /dev/sdb1 and /dev/sdc1 which is the one that grub chose, again non-existent. /dev/sdb1 is actually a Zipdisk drive but I tried it anyway since there is no zipdisk in there. It never booted so I am throwing in the towel, figuring that in all the messing around, I have corrupted something and wasted about two weeks on and off trying this, that and the other. I have a good 32 GB drive left over from a computer that died last year so I will just clone it from the working system that is sending this email. The drive that can't boot but is otherwise fine will now be the second drive and will mount as /home where all the important stuff I used it for can still live. The only good thing about this exercise is that I know a lot more about what grub does than I did and I also discovered that while I had perfect backups of the home directory, I had failed to set rsnapshot to backup /boot which was quite a stupid oversight on my part. /var, /etc and several other directories off of / get daily backups and I could have sworn /boot did but it's not there so I have been doing a lot of industrial-grade swearing lately. Grub is a very fine tool when used properly and I do believe that there should be a pristine way to make a disk bootable that is intuitive and automatic plus unaffected by the configuration of any other drive on the system, like the old sys command in DOS to make any DOS diskette bootable. The unix incarnation of the sys command would have to do a lot more such as verify that you have a kernel and modules ready to go plus consult your /etc/fstab and /etc/default/grub files but that shouldn't be a real problem. One would basically do the grub install in a a total jail so it would come out set as if one had just been running the installer and this was the only drive on the system. Thank you all for your help and sorry that it took so long to determine that nothing simple was going to work. Martin
Re: A Grub Boot Question about initrd
First I greatly appreciate all this information as the idea is to
fix a problem I probably created long ago though I am not sure
how but the short story is that apt-get upgrade ran update-grub
and update-initramfs late last Fall and I was able to rescue it
but it happened again at the end of April so I figured I had
better fix it correctly since I didn't know it was a ticking
bomb.
Felix Miata writes:
> Martin McCormick composed on 2021-06-05 12:46 (UTC-0500):
>
> > I have a plan but I need some more information. Is there any
> > personalization done by the boot setup process? Do our UUID's
> > or any other specific information pertaining to the installation
> > make it in to the initrd files?
>
> Dracut includes a root=UUID= statement in the initrd. A root=
> statement on
> the Grub linu* line overrides it. The override can be any of the accepted
> forms,
> including root=LABEL= and root=.
Good to know.
> The translation is easy. UUIDs are assigned to devices. The device names
> are
> acceptable substitutes, just as they used to be the only option before
> libata made
> device names capable of playing musical chairs. If devices also have
> labels,
> labels can be used instead of device names.
Very much like the reasoning behind udev which is a God-send if you
have multiple sound cards as one example.
> UUIDs were designed for computer scripts, not human brains. You'll need
> to make a
> conversion, but instead of UUIDs, I highly recommend using labels when
> you know
> device names will be different on the system migrated to. UUIDs are
> appropriate
> too, just rather unwieldy unless scripted.
There's 1 UUID for the root file system in /boot/grub/grub.cfg
which is the file one must not normally edit by hand. It
reads
menuentry 'Debian GNU/Linux' --class debian --class gnu-linux --class gnu
--class os $menuentry_id_option
'gnulinux-simple-658da8df-942e-4ad7-8c5b-695f2f2eb4ed' {
> Grub provides a shell. From the shell it's possible to boot using the
> information
> you have. Instead of trying to figure it all out in advance, drop to the
> shell and
> use the device names you know. It's really not hard if you have a copy of
> a grub
> menu from the two PCs planted in your brain or on paper. Once you've
> booted, it's
> easy to fix everything up by running grub-mkconfig, and if necessary,
> /etc/default/grub.
>
> > As an aside, one ought to be able to do something like
> > this. It makes life a lot simpler. Both systems are using the
> > same kernel and versions of the same processor the only real
> > differences are the UUID's. The grub configurations of both are
> > the same down to the serial console.
>
> Don't let the massive volume of data in grub.cfg mislead you. Its primary
> job is
> to find and load a kernel and initrd. If you know where they are and
> their names,
> none of the menu components or apparent search and identification bloat
> are
> necessary. Before Grub2 you could simply tell Grub's shell the root
> device, the
> kernel name (with associated parameters, most of which aren't actually
> necessary),
> and the initrd name, then boot. With Grub2 you may need to precede the
> root device
> name with loading a module or two or three, which you see in your copy of
> a
> grub.cfg, then proceed with the important three. I do a lot of cloning,
> so I've
> done it often.
Thanks again. I was starting to get discouraged but I
will try using actual labels since I thought you really shouldn't
do that.
Martin
Re: A Grub Boot Question about initrd
Reco writes: > On Sat, Jun 05, 2021 at 12:46:13PM -0500, Martin McCormick wrote: > > I have a plan but I need some more information. Is there any > > personalization done by the boot setup process? > > Yes. One of the GRUB's tasks is to supply kernel which is about to boot > with root=... cmdline parameter. Root filesystem UUID can be used for > this. > > > > Do our UUID's or any other specific information pertaining to the > > installation make it in to the initrd files? > > In Debian - no, unless you include it there for some bizarre reason. > It's not needed for the things initrd usually does. > > > > If that is so, then two computers using the same > > processor type should be able to use copies of the same initrd files > > and the only thing that is personalized on an individual computer > > is all the grub configuration in which the UUID's of at least / > > and /swap partitions are sprinkled throughout grub.cfg and > > /etc/default/grub. > > It's not the CPU difference you need to worry about. > Different SATA controllers, video cards, NICs - i.e. what they call > periphery devices - those things require different kernel modules that > should be (or could be) used in early boot process, and therefore need > to be included in initrd. > > Luckily, Debian uses initramfs-tools for building initrd, and > initramfs-tools should build initrd with everything and a kitchen sink > included (MODULES=most in /etc/initramfs-tools/initramfs.conf). > > > > One should be able to write a program to get the > > appropriate UUID's out of fstab on the working system > > and translate them in to corresponding UUID's for the system on > > the operating table. > > Er, they've invented filesystem labels for exactly this many decades > ago. > > > > As an aside, one ought to be able to do something like > > this. It makes life a lot simpler. Both systems are using the > > same kernel and versions of the same processor the only real > > differences are the UUID's. > > Perfectly possible for the last 15 years or so. Assuming Debian and > MODULES=most, of course. > > Reco > > It sounds like I haven't missed anything obvious so I will see if I can write a perl script or some other text-muncher that will recreate the grub configuration of the working system but with the UUID's of the non-working system plus a grub.cfg file exactly like the grub.cfg file on the system that refuses to boot but with the correct UUID labels describing the boot partition on that system plus a copy of the kernel and it's module directory. As for partition labels, I have always thought the name was much easier to deal with than the 36 randomly-selected characters that make up the UUID on a unix partition but UUID labels are supposed to be unique and are what you encounter today so I will see if I can make the script modern compatible. Thanks to you and delop...@gmail.com.
A Grub Boot Question about initrd
I have a plan but I need some more information. Is there any personalization done by the boot setup process? Do our UUID's or any other specific information pertaining to the installation make it in to the initrd files? While reading about the boot process, it doesn't appear that the initrd files or initranfs are personalized with anything pertaining to this computer and this installation. If that is so, then two computers using the same processor type should be able to use copies of the same initrd files and the only thing that is personalized on an individual computer is all the grub configuration in which the UUID's of at least / and /swap partitions are sprinkled throughout grub.cfg and /etc/default/grub. One should be able to write a program to get the appropriate UUID's out of fstab on the working system and translate them in to corresponding UUID's for the system on the operating table. If the target system actually boots, it is probably a good idea to run update-grub to make sure that still produces a working boot but this would still more than likely produce the same results if this process works in the first place. It's also possible that the reconstructed grub setup is okay except for the drive designation which usually starts out as /dev/sda1. On my good Buster system, this is now /dev/sdc1 and on the sick one, the attempt is being made on /dev/sda1. The idea here is to copy the concept of what is happening rather than the literal configurations which definitely will never work unless one used dd to generate the clone drive and I have actually done that once and it worked but the cloned system was then adapted for other uses. Here, all I want to do is rescue the boot process so it lives on and not have to reinstall everything else. As an aside, one ought to be able to do something like this. It makes life a lot simpler. Both systems are using the same kernel and versions of the same processor the only real differences are the UUID's. The grub configurations of both are the same down to the serial console. Martin
Re: Boot Repair. Still Going Round and Round.
I placed the ailing drive back on a good Linux system and mounted it as /dev/sdd1 /mnt and ran the following commands on it: #!/bin/sh #mount the drive being repaired. Uncomment lines as needed. sudo mount /dev/sdd1 /mnt cd /mnt/boot #installing to the mounted disk sudo grub-install \ --boot-directory=/mnt/boot/ /dev/sda Installing for i386-pc platform. Installation finished. No error reported. root@wb5agz:/# But wait. There's more. root@wb5agz:/# update-grub --boot-directory=/dev/sda Unrecognized option `--boot-directory=/dev/sda' Not good. Continuing on to update initramfs. #Isolate the disk. sudo mount --bind /dev /mnt/dev sudo mount --bind /dev/pts /mnt/dev/pts sudo mount --bind /proc /mnt/proc sudo mount --bind /sys /mnt/sys That all worked. sudo chroot /mnt root@wb5agz:/# update-initramfs -c -k 4.19.0-5-686-pae That appears to work. root@wb5agz:/# update-grub Generating grub configuration file ... Found linux image: /boot/vmlinuz-4.19.0-5-686-pae Found initrd image: /boot/initrd.img-4.19.0-5-686-pae Found linux image: /boot/vmlinuz-4.9.0-9-686-pae Found initrd image: /boot/initrd.img-4.9.0-9-686-pae Now this ruins everything. Found Debian GNU/Linux 10 (buster) on /dev/sdc1 done This was a chroot environment but it appears that /dev/sdc1 was recognized as the boot source for this external drive. /dev is part of the system. The external drive normally lives in another system and is the only boot source which is why it should be /dev/sda1. Is there any way to run update-grub from grub itself? The system this external drive is meant for normally only has 1 boot drive which is the one that is currently confusing grub. If I could run install-grub and update-grub from the dead system, there would not be any other bootable drives and the only game in town would be /dev/sda for the boot record and /dev/sda1-5 for the boot drive. Understanding what is supposed to happen isn't particularly difficult but getting grub to think simple and easy Putting the drive on another system and hoping for no contamination seems to be a lot easier said than done. Martin
Re: Boot Repair
Weaver writes: > Well, let us know how it goes, because I've noted a few visually > disadvantaged users on the list, and they would find the reference > useful. I have found out that grub is very accessible if one has defined a serial console and there is a working serial port on the target system. In this case, both conditions are true. The next thing one needs is a talking terminal which is no problem if one has another computer equipped with a serial terminal program like microcom or what I consider the gold standard, kermit which apparently has too many dependencies to be part of the Debian distributions any more. Kermit has a decent scripting language so one can save the commands that work, even the commands that involve entering a huge string in which one typo means completely starting over again. This means you can completely repeat all the things that work each time and feed it all in again in a fraction of a second. Talk about working smarter as opposed to harder. While I call kermit the gold standard, the gold standard for scripting is expect so one can call unix applications from the login shell to any valid command, read the output and generate commands as if one was there. You can even simulate human typing rhythms to defeat attempts to detect robots. I'd love to see a good CAPTCHA solver with OCR that was so good that CAPTCHA designers would go out and find honest work but I digress. This is actually a systemic problem these days when dealing with sick machines. Nobody is selling new desktops with RS-232 native serial ports and that is fine as long as there is an alternative way such as a bluetooth interface or ssh network connection. The dream solution would be a local network login covering all the lights-out conditions such as BIOS configuration and failure to boot as in this situation where grub is confused. Before I retired, some of our newest servers used management interfaces and ipmitool where one could turn power on and off, do BIOS setups and other configuration remotely. It was so cool to be able to do those things on a system in another town without leaving the chair or grabbing a go bag and blowing a whole day just to flip a couple of switches. Of course, if it was that simple, we usually could call someone we trusted at one of our remote campuses and ask them to flip the switches but I'm sure you see the advantage of remote management. For folks who are blind, you treat all those things as if they were halfway round the Earth instead of sitting less than 1 meter apart. They are all headless even if I can extend my arms and touch both machines. I think the grubdisk2 GUI app is basically a lost cause but that's the rule when dealing with accessibility. When it's done wrong, you chase down endless rabbit holes all day and muse as to how there must be some way to turn the sausage machine backwards and have live farm animals running away from the other end. There was an American country and Western song back in the early seventies which had a line at the end of each verse that went, "Work your fingers to the bone What do ya' get? Bony fingers." I think the best course right now is to take my bony fingers and workup a kermit script to interact with grub and get it to produce one boot and then use the running system and grub to fix itself. So far, nothing else is less work. I do appreciate your telling me about grubdisk2 because sometimes, these things turn out to be life savers and you have to try the rabbit holes to know for sure. Martin
Re: Boot Repair
Weaver writes: > https://www.supergrubdisk.org/ The site recommends downloading the hybrid version of grub2disk so that is what I did because all the Linux boxes I have are x86 hardware and have CD technology built in. This is quite an interesting creation. The ISO image is a wee bit over 16 MB in size and, as I suspected, the package includes no screen reader modules whatsoever but I did mount the CD after burning it and ran find . -name "*" -print and there are serial modules sprinkled throughout the distribution. There are occasional references to a serial console. In some of the documentation I have found on the site, I haven't found one iota of text as to how to make this console work but if computer users who are blind can access this serial console, that is like finding gold in them thare hills. Tomorrow, I will look further for any hints as to how to make the serial console appear but I actually did read the words "serial console" on that site. When I listed all the files on the CD, I also ran across the following: ./boot/grub/i386-efi/morse.mod ./boot/grub/i386-pc/morse.mod ./boot/grub/x86_64-efi/morse.mod If this has to do with outputting text in Morse Code, I know Morse since we amateur radio operators once had to know it to get our licenses and as long as it is sending at a reasonable rate which, for me, stops at about 20 words per minute, is perfectly useful to read the output. I didn't even see any references to Morse Code on the site so it's another way to make this useful. The PC being used to run this CD does have a piezo buzzer on the mother board so if there is a way to make it sing in Morse, I may not need the serial console but it certainly would be nice to know all there is about both of those fall-back methods. Thanks to anybody who knows where real sentences are that explain the serial console or the possible Morse code output. Martin WB5AGZ
Re: Boot Repair
Weaver writes: > On 03-06-2021 03:59, Martin McCormick wrote: > > Is there any free utility that can run in Linux which helps one > > rebuild a corrupted boot configuration? > > https://www.supergrubdisk.org/ Thank you very much as you did answer my question perfectly but I did not stop to think about all the possibilities of the form the solution might take. So, as a computer user who happens to be blind, is this stand-alone application using a linux kernel containing the speakup modules? On the Linux live CD's, one can get those to talk by striking the S key as the system boots up and then one can hear what is on the screen as one works. Do you know what kind of kernel it uses? Martin
Boot Repair
Is there any free utility that can run in Linux which helps one rebuild a corrupted boot configuration? I have a disk which is currently out of it's usual place as the boot drive for a debian system. The past two times that Buster updated grub, the drive became unbootable after the update. The drive, itself appears to be perfectly good and I think the problem which makes the update kill the drive is related to a dd copy I made some years ago of one drive to another so most of what is there is normal. After the second killing of the drive, I started to determine what is misguiding update-initramfs as grub-install seems to produce a grub.cfg file that is looking for all the right UUID's but when the system boots, grub now fails by trying to find a UUID that must have belonged to a now deceased system as it no longer appears in the fstab of either the newly-dead system or another system which is alive and well and being used to try to revive the injured drive. Everything needed to produce a valid boot is there if only I can run something that will reconstitude the boot image so that it looks for the right UUID's. I do remember seeing this message as the update ripped through the new grub: update-initramfs: Generating /boot/initrd.img-4.19.0-5-686-pae W: initramfs-tools configuration sets RESUME=UUID=6f6f4373-45a3-4c16-97b4-f62613 fe6d3b W: but no matching swap device is available. That UUID should start with a 3, not a 6 as the blkid for /swap is what should be there. I am not totally sure where tthe UUID that starts with 6f6f comes from but that's also the UUID one sees when grub crashes and burns on liftoff when trying to boot from that drive. Martin
Grub on Dead Disk solved
I missed the INSTALL_DEVICE and now the script works. The next step is to see if the drive boots but I just forgot that one important detail. Sorry to waste anyone's time. Martin
Grub on Dead Disk
I had this same problem late last Fall on this same drive and am not sure what is going on because there is another Linux system here whose drive is arranged exactly the same way. An update in March modified grub and I didn't even give it a thought because that system just works but after an update a couple of days ago, the dead system starts a boot but grub complains about neither possible image being bootable. When I rescued that system last Fall, I was advised on this list to do the following which worked perfectly by the way: >If you want a grub-install command that writes /boot/grub files >somewhere onto /dev/sdd then you will first have to mount the desired >target boot partiton of /dev/sdd on some mountpoint that you choose, >and then run a command something like this: > sudo grub-install >--boot-directory=/some/mountpoint/where/is/the/sdd/boot /dev/sdd I mounted the drive on /mnt so looking at /mnt gives you / and the directory where the correct files are is then /mnt/boot or possibly /mnt/boot/grub. I created the following shell script which I named do_grub. #!/bin/sh sudo grub-install \ --boot-directory=/mnt/boot/ I get the following no matter where I point boot-directory: ./do_grub [sudo] password for martin: Installing for i386-pc platform. grub-install: error: install device isn't specified. I don't remember doing anything else. I think this time I may also need to do update-grub on the currently bootless drive. As with the last time this happened, the dead drive passes all fsck tests and the first time I ran fsck on it, nothing needed fixing. This is one of these problems that hardly ever comes up which means that when it happens, one spends/wastes a lot of time doing duckduckgo and puzzling. There should be a way to automate or at least prompt the person running the recovery attempt to find the right information to get things up and running if at all possible. It's all there such as the grub file in /etc/default which should have the uuid of the/ and swap partitions. Right then, one could see if the uuid's are correct and get a proper boot going in which one could then rerun update-grub if necessary. Right now, it's just fumble and fiddle and wonder what happened. I must have something set wrong to cause the apt-get upgrade to build a non-functional grub since the system in question made a number of reboots successfully between about last December 1 and now. I also remember reading a message about problems with swap which is on /dev/sda5 when the drive is booted. I found the messages log which shows swap as correctly mounted and working before the upgrade. Is there another log which might still have that message from apt-get upgrade. The message was not captured at the time. I have been using Debian on several systems for a number of years and this one system is the only one which seems to fall down every time grub is touched. That indicates I need to check one of the configuration files which probably has a wrong partition ID or something similar. I am just glad I have another Linux box to mount the no-boot drive on and that the drive, itself, does not seem corrupted just as the last time this happened. Thanks for any constructive ideas. Martin McCormick WB5AGZ
Is there any way to snoop on a USB port?
I have a Windows box that has software on it which programs two-way radios and it would be nice to know what the radio and computer are saying to each other. After trying a Windows application that reportedly can capture serial port traffic, I find that it doesn't appear to work with usb ports and unix/linux is my preferred world anyway so is there any sort of hardware that would pass through a USB connection from the Windows box to the radio and let me siphon off the traffic to a linux system and log it? The Windows app I tried to use has been around for a decade or more and probably works well with RS-232 ports but the traffic I need to grab comes from a usb device that creates /dev/ttyACM0 if plugged in to a Linux box and comm2 on the Windows system When I tried it today, it did nothing but complain that it was not connected. It finally dawned on me that it probably sees no serial ports at all as it is supposed to automatically find and log all port I/O and this is a relatively new HP Pavilion desktop computer which has no native RS-232 ports or parallel ports on it and, even if it did, the connection from the radio to the usb port is a usb plug with the usb hardware in it and a cable that plugs in to the radio that would most likely not be practical to tap. Thanks for any good thoughts. Martin WB5AGZ
fail2ban Squawk
I was attempting to setup a systemd timer and checking the syntax of that when I ran across a complaint from the fail2ban program which is a bit confusing. It reads: /lib/systemd/system/fail2ban.service:12: PIDFile= references path below legacy directory /var/run/, updating /var/run/fail2ban/fail2ban.pid → /run/fail2ban/fail2ban.pid; please update the unit file accordingly. So I looked in to that file and the actual line they were referring 2 is numbered 15 and points fail2ban.pid to /var/run/fail2ban/fail2ban.pid where it certainly lives with a recent date. What is the problem exactly? Enquiring minds want to know. Thanks for any and all constructive ideas. Martin McCormick
Re: Web-bot tarpit aka spider trap (was: swamp rat bots Q)
It's nice to see that I am not the only sick puppy out there. At 69 years old, I still don't have much trouble with getting in touch with my inner 12-year-old when it comes to intrusive marketing which is so prevalent these days. I found our old dial-up modem in a box of odds and ends 2 years ago and wondered if it could read callerID tones sent after the first ring. It can so I started on a perl program that initializes the modem for callerID and then compares the strings received with a pair of files, one of which is called scum and contains callerID name packets of folks we don't want to talk to. The other is called good and looks for names of friends or anyone else we like hearing from. It is actually scanned first and causes the program to abort. If anyone's name matches a name in scum, or the caller's ID appears to be blocked or, in one case, matches a whole exchange, (first 3 digits after the area code), I call a subroutine that makes the modem answer for half a second then drops the call. We were bombarded with garbage calls all day long until the US presidential election and it was so satisfying to hear the program kill the call by answering just as the second ring began. I also installed subroutines that looked for the word "SPAM?" just before the name or "ROBO?" also just before the name. We now get very few unwanted calls but occasionally, we'll get a call from lala-land from someone we don't know who lets the phone ring until the answering machine picks up and then fails to leave a message and I tell my wife, "I'll go put them on the juke box." especially if it looks like the name of a business with which we have no relationship. Our phone is very quiet these days except for legitimate calls. Martin McCormick
Re: Cron Jobs and Time Zones Has Anything Changed?
Andrei POPESCU writes: > On Jo, 03 dec 20, 07:39:14, Martin McCormick wrote: > > > > So, I need to read more general information about the > > differences between systemd and what we've been using up to > > recently. > > The Wikipedia page and/or https://systemd.io might be a good place to > start. > > Kind regards, > Andrei I've had a chance to investigate this more and the first thing I did was to go to wikipedia which told me about systemd, the on-going argument about it VS older ways to build unix-like systems and a time line when systemd began to take hold which was around 2015 when I retired from work so it kind of sneaked up on me and I didn't realize that I've been using it for 5 years, well, at least I didn't think much about systemd having different resources. I've used udev rules in making sound cards come up in the right order and that's totally a systemd thing. While searching for ways to use cron with different time zones, I found out about something called systemd timers just mentioned in this thread and it appears they definitely will do the job but one must magically have made the connection between this concept and the concept that cron, the usual go to resource for making lighting come on at a certain time, purging stale files or backing up the system now has a new kid on the block called systemd timers. One can even list all the active systemd timers https://www.maketecheasier.com/use-systemd-timers-as-cron-replacement/ $ systemctl list-timers And, sure enough, I had a number of them ticking away. An on-going problem about self-education is that it's easy to limit the scope so much that we miss connections. Systemd timers doesn't even sound like a replacement for cron but think of it as cron on steroids. One of the things in the wikipedia article about systemd was a complaint by someone that it's just too complicated. All I can say is that maybe or not that is true but that's just life. Start simple. Make more and more complexity as problems with simple show up. One day, try to make things simple again. Lot's of luck with that. I'm not so sure that being blind makes nearly as much difference these days as it once did, but making connections that relate one knowledge base to another in a meaningful way will always be a problem for us. Martin
Re: Cron Jobs and Time Zones Has Anything Changed?
> On Wed, Dec 02, 2020 at 01:58:45PM +, James B wrote: > > This might be wrong, but as far as I understand doesn't systemd > > now have the ability to manage cron jobs (as well as mount points, > > home folders and other things)?. Is there anything in this newer > > functionality that might make such a thing (re the request at the > > beginning of this thread) possible? > > Yes, I pointed this out to OP last time OP asked this exact question just a few days ago, so I don't know why they are asking again. I am guilty as charged but haven't yet found the relevant information as to how systemd helps solve this issue. Systemd is praised to the rooftops by some and cursed just as vehemently by others and it is what we are now using but it feels mostly like unix has always felt. I am obviously suffering from the worst sort of ignorance syndrome which can really bite in that sometimes, we have an idea what we don't know and other times, we don't even know that we don't know and that's really frightening. So, I need to read more general information about the differences between systemd and what we've been using up to recently. Martin McCormick
Re: Cron Jobs and Time Zones Has Anything Changed?
Greg Wooledge writes: > I was vaguely thinking of a similar approach. Set up a job that runs > every hour, or across a set of hours that will cover all the possible > cases that you care about, in your crontab. Within the job itself, > set a TZ variable and determine the time in that time zone by whatever > means necessary, and then either abort or continue based on that time. > > This is also similar to how one approaches a complex date-based task > such as "run on the second-to-last day of each month". For that one, > you can set up the job to run on the 27th through the 30th every > month. Then within the job itself, determine whether it's the > correct day, and abort if it's not. What I was thinking of is a modification to cron which should integrate nicely with what cron already does. Crontab would have a new field at the beginning of each line which could normally be left at "default" which would be the normal behavior that we are used to. If someone wanted to run a job at 15:00 each day in let's say Japanese time, the first field of the line would read Asia/Tokyo instead of default. The line might look like Asia/Tokyo 28 15 * * 1-5 sh -c ". $HOME/.master.env;beep -f700 -l500" Since all unix-like systems start out with UTC and use those /usr/share/zoneinfo data base files to calculate what local time is, that information is handy in the time() function. localtime(time) gets you the adjusted number of seconds for your locale arranged in a structure containing fields for the current year, day of month, day of the week plus the hours, minutes and seconds with the adjustment for Summer or Winter for that zone. The sample line above would cause cron to grab the current epoch in seconds (UTC), feed that to localtimebased on rules for /usr/share/zoneinfo/Asia/Tokyo and then all those values to match the fields on the rest of the line. The time of 15:28 or 3:28 PM in Tokyo occurs around 01:28 in the Central US time zone and that's when your computer would have beeped. This would happen Monday through Friday Japanese time which still would be Monday through Friday in the US but early in the morning. If the time referenced in Tokyo had been 7:00 in the morning , it would happen the previous evening in the US. As long as one designated the time zone correctly and doesn't forget that 07:00 on Monday morning in Japan equals 5 or 6 o/clock on the evening of the previous day, it should just work. I haven't looked at the C code for cron, but I have written a few perl scripts that do things with time and dates and the current epoch-based number of seconds since utc Midnight January 1, 1970 is based on the C modules such that one's current wall-clock time is time(localtime). Just a thought Martin
Cron Jobs and Time Zones Has Anything Changed?
In a recent discussion, someone indicated that there might be a way to set individual parts such as accounts on a unix system so that cron could use another time zone if needed to kickoff jobs on that system based on the time in another country. As far as I understand cron, one can set the system's time zone to only one value which is usually one's local clock time and that works very well since system logs and cron jobs all agree with what is appropriate for one's location. I record a news broadcast from one of the BBC services every week day at 17:45 British time. When Europe and North America stop or start shifting daylight in Autumn or Spring, there's a really good chance of missing some of the broadcasts if one doesn't think about it since these shifts don't all happen on the same time. One can certainly get the time anywhere as recently discussed by setting the TZ environment variable but, if you tell cron to trigger a job at 17:45, it only knows when that is based on the entire system's local time. Has anything changed recently to make this logic obsolete? In my case, I just have an old Linux box for which I set it's system time zone to Europe/London and call it good but this could get out of hand if one had more than 2 or 3 such schedules. One could also setup VM's if you have the memory to spare but this adds a lot of resource usage and complexity to the job at hand so my question is basically, has anything fundamentally changed in the way cron is used? This is not a complaint at all. I was first introduced to unix-like systems in 1989 and immediately knew that this was the sort of OS I wanted to stick with in amateur radio and technical tinkering in general. Martin McCormick WB5AGZ
Re: Fixing a Grub Foul-up Solved!
David writes: > Your lack of success is because the the command you used has designed > behaviour to install the grub bootloader to the boot sector of > /dev/sdd, and also install the grub files you listed into the current > system /boot/grub (which was not on sdd at the time). That is the > reason why you see those files on /dev/sda1, because it was the boot > partition at the time you ran the command. Aha!! that makes perfect sense now that I think a bit. > > If you want a grub-install command that writes /boot/grub files > somewhere onto /dev/sdd then you will first have to mount the desired > target boot partiton of /dev/sdd on some mountpoint that you choose, > and then run a command something like this: > sudo grub-install > --boot-directory=/some/mountpoint/where/is/the/sdd/boot /dev/sdd I tried it and by Joe, it wrote to the correct drive so I don't feel quite so paranoid about using grub. Interestingly, I goofed again and grub ended up in what is the / directory instead of /boot/grub so it still didn't work but I knew immediately that the new grub was working because there was no error message about symbols not found, etc. I mounted the drive back on the good system and simply removed the grub from the top of the tree and then did the grub-install command again but thihs time, I installed to /mnt/boot. It wrote to /boot/grub as it should have and the system came right up. There was a minor glitch when I powered the box up as the keyboard reported a stuck condition and advised me to press F1 to continue. I thought this was a bit amusing since the keyboard appeared to be malfunctioning but F1 did the trick and about a tenth of a second later, I heard the beep that grub plays when the kernel is about to fire off. In short, the faulty grub that made it onto the system was all that was really wrong. Thanks to a lot of you, I appreciate grub more as this has been quite a little mini course in what it does. Martin
Re: Fixing a Grub Foul-up, Not There Yet.
I am going to respond to one of my earlier posts as it doesn't help things at all to spread misinformation which I am guilty of, here. "Martin McCormick" writes: > I appear to be using grub, not grub2. No. It's grub2. Old Grub is now grub-legacy and is probably a dead fly on somebody's wall by now. > There's an extra little wrinkle in that, as a computer > warier who happens to be blind, grub isn't really accessible in > that you can not get direct access to it via a serial port and > terminal, say, from another computer that is actually working. I was simply wrong there. Of course, one has to have the lines now in /etc/default/grub that used to be in menu.lst but the idea is the same. If one has a serial port which is available at boot time, grub should work headlessly. The issue with the instance of grub that seems to have a run-time error due to a problem with modules, may be unusual because it may actually be a goner before it runs since it doesn't get to load it's modules. Martin
Re: 780 files in /usr/share/zoneinfo/
Michael Stone writes: > The kernel, compressed, is larger than that. The initrd needed to boot the > kernel is also typically larger than that. A modern system has more CPU > cache than that. At some point trying to save bytes is a waste of > developer > and administrator effort, and 3.5MB in 2020 is well past that point. If > you > want a minimal system, debian isn't for you. Instead, you'll need to hand > craft every file to make sure it isn't "wasting space". If that's your > thing, great. But it's just not a focus for debian. About the only place one still needs to think this way is with embedded systems where the computer is there to manage a machine of some kind, anything from a lathe to a food processor to a cement mixer, whatever . General-purpose computers are optimized to have as many resources as one can cram in to a higher and higher-density box so a few MB here or there aren't noticed but embedded systems are optimized with different priorities and one may discover that this box may be lightning fast but a bit skimpy on data storage. I am thinking of things such as cable TV boxes and dedicated audio-visual appliances that use DSP to emulate complex and expensive hardware by using mathematical algorithms that cause the system to decode digital TV signals or route internet traffic rapidly. If you aren't in to trying to modify some sort of embedded system to do something it wasn't originally designed to do then ram and storage are getting cheaper by the day and some things just aren't worth worrying about. Martin McCormick
Re: 780 files in /usr/share/zoneinfo/
Andy Smith writes:
> Hi Martin,
>
> On Sat, Nov 21, 2020 at 08:48:51PM -0600, Martin McCormick wrote:
> > find . -name "*" -exec ls -l {} \; \
> > |grep -F / \
> > | awk ' { total += $5 } END { print total }'
> >
> > That usually just adds the sizes of all the files it can
> > find all the way through the tree.
> >
> > If this is not an accurate way to determine how many
> > bytes there are in a directory then that would be the reason for
> > the discrepancy.
>
> The same file can be reached by multiple names. So by doing this you
> end up, in this case, with a ~256x amplification.
>
> A simple "du -sh" does a better job here!
>
> > cron only works in the time zone for wherever the TZ for the
> > system is set.
>
> Ah, I see. I've never tried it but I believe that systemd timers can
> have a time spec that includes time zone, so you can set timers that
> fire on a different time zone to that used by the rest of the system.
>
> $ systemd-analyze calendar '11:00 Europe/London'
> Original form: 11:00 Europe/London
> Normalized form: *-*-* 11:00:00 Europe/London
> Next elapse: Sun 2020-11-22 11:00:00 UTC
>From now: 6h left
>
> Cheers,
I do appreciate being corrected, here. What we really want to
know, here, is how much precious disk space is occupied by
whatever data base we are interested in. Links make copies of
files appear to exist when the data were only written once even
Martin
Re: Fixing a Grub Foul-up
Dan Ritter writes: > Here's what you can do: > > On a good system, mount your drive. Let's pretend that it's > recognized as /dev/sdg, and you have a /boot on /dev/sdg1 and > a root partition on /dev/sdg2. > > ls -al /dev/disk/by-partuuid/| grep sdg > > will get you the partition UUIDs for that disk. One of them will > be for /dev/sdg1 and another for /dev/sdg2. > > The kernel really likes these as root filesystems identifiers. > The kernel parameter that you put in /etc/default/grub is > > ROOT=PARTUUID=dddf0dd6-dd6b-d542-9eac-015a765cd6f6 > > although you will want to substitute in the appropriate > part-uuid for /dev/sdg2. > > Finally, you can run > > grub-install /dev/sdg > > to get a new copy of grub into the master boot sector of the > disk. > > Hope that helps, > > -dsr- This does help a lot and I have read similar examples how to work on a drive that has been mounted on a different system than the system on which it will ultimately be used but I am still doing something wrong and the results are dangerous to say the least. At one time, the otherwise good drive was mounted on /dev/sdd with the root partition on /dev/sdd1. I typed sudo grub-install /dev/sdd. It ran for a few seconds, announced that grub was installed without any errors and exited. After looking at /dev/sdd1/grub and seeing no updated date stamps, I had a sinking feeling and looked at /dev/sda1 which is the boot partition on the system I haven't killed yet and, sure enough, grub-install had run on that drive. $ ls -lt /boot/grub total 2372 drwxr-xr-x 2 root root 12288 Nov 29 11:26 i386-pc drwxr-xr-x 2 root root4096 Nov 29 11:26 locale -r--r--r-- 1 root root7276 Sep 3 05:43 grub.cfg -rw-r--r-- 1 root root 2396122 Sep 3 05:43 unicode.pf2 -rw-r--r-- 1 root root1024 Jun 29 2019 grubenv drwxr-xr-x 2 root root4096 Jun 29 2019 fonts It didn't even touch any part of /dev/sdd1. With trepedation, I rebooted the good system and thankfully, it came right up since I hadn't modified /etc/default/grub. That was a bit of good luck but I thought it was supposed to write to /dev/sdd1 which would translate to /dev/sda1 when the drive was connected to the controller of the system that is presently belly up. I suspect the problem is the issue with the modules which another poster described. What am I failing to do to make the changes occur on the designated drive? Having it write this kind of stuff to drives other than the desired target is scary. Thanks for a good explanation and I may not be so lucky next time. Martin
Re: Fixing a Grub Foul-up, Not There Yet.
Dan Ritter writes: > in /boot/grub/menu.lst > > serial --unit=0 --speed=9600 --word=8 --parity=no --stop=1 > terminal serial > > (yes, that's two lines) > > I hope that helps. > > If you want the option of either serial or console access, > replace the second line with > > terminal --timeout=10 serial console > > The default will be serial, but if you press a key on the > console within 10 seconds, it will go there instead. > > -dsr- Thank you. That is a tremendous thing to know. I thought there was something serial in grub but I couldn't remember. This is the first time I ever had any real trouble with grub and I can put this drive back on the working linux box and modify that file, assuming the change would take place on the next run of grub. Martin
Re: 780 files in /usr/share/zoneinfo/
Andy Smith writes:
> Hi Martin,
>
> Are you sure about this? There is no Debian or Ubuntu host I have
> access to that has a /usr/share/zoneinfo/ that contains more than
> 4MiB of data. For yours to have 256 times this much is quite an
> aberration. What did you type to determine that your
> /usr/share/zoneinfo/ has 1GiB of data in it?
find . -name "*" -exec ls -l {} \; \
|grep -F / \
| awk ' { total += $5 } END { print total }'
That usually just adds the sizes of all the files it can
find all the way through the tree.
If this is not an accurate way to determine how many
bytes there are in a directory then that would be the reason for
the discrepancy.
>
> > I've wished one could just set certain parts of the
> > computer to other times but I can also understand why this could
> > be a problem.
>
> You can set any process to have a different time zone by use of
> environment variables.
>
> $ date
> Sat 21 Nov 21:34:55 UTC 2020
> $ TZ=America/Los_Angeles date
> Sat 21 Nov 13:35:04 PST 2020
That is very true but cron only works in the time zone
for wherever the TZ for the system is set.
On the system I have set to British time, my local login
shell has TZ=America/Chicago so I read Central Standard Time for
file time stamps but if I set a cron job, it runs on either
British Summer Time or British standard time which is the same as
UTC during Winter.
> Cheers,
> Andy
Re: Fixing a Grub Foul-up, Not There Yet.
Felix Miata writes: > Save yourself many keystrokes by using the symlinks in the root directory > instead > of the long-winded full version-named /boot/vmlinuz-4.19.0-5-686-pae This is wonderful to know and in the root or / directory of this disk, there is initrd.img, initrd.img.old, vmlinuz and vmlinuz.old Those all point to valid targets. I presently have the no-boot disk mounted on a working linux system where it's root directory is /dev/sde1 and the current links plus the old links are as follows: lrwxrwxrwx 1 root root32 Jun 26 2019 initrd.img -> boot/initrd.img-4.19.0-5-686-pae lrwxrwxrwx 1 root root31 Jun 26 2019 initrd.img.old -> boot/initrd.img-4.9.0-9-686-pae lrwxrwxrwx 1 root root29 Jun 26 2019 vmlinuz -> boot/vmlinuz-4.19.0-5-686-pae lrwxrwxrwx 1 root root28 Jun 26 2019 vmlinuz.old -> boot/vmlinuz-4.9.0-9-686-pae I finally have found something that may be a clue to what's actually wrong. While trying to manually make that drive boot, I got this: grub rescue> set prefix=(hd0,1)//boot/grub grub rescue> insmodnormal Unknown command `insmodnormal'. That was a good old syntax error so I tried insmod normal with a space grub rescue> insmod normal error: symbol `grub_calloc' not found. I'm pretty sure that shouldn't happen at all and is what's behind the failure to boot. I haven't found any uuid's that are different although I first thought I had as I looked at some links which had uuid's but they were good when I looked at the actual partition. It's easy to go down a rabbit hole if one doesn't watch out. I think there may be something about grub that got left out or changed during the upgrade. Martin Martin
Re: 780 files in /usr/share/zoneinfo/
writes: > Suppose a hacker logs into your computer from far, far away, say > from somewhere in Nepal. > > Surely you'd want this person to see the time adapted to their > locale? That's the least courtesy you can be expected to provide? > > ;-P > > Now putting my tongue out of my cheek again: in Unix, a computer > "has" no time zone or language -- people have those. And since, > again in Unix, several people can be logged in [1] at the same time, > it's up to the user's environment [2] to decide on time zone, > language, etc. > > This concept is surprising at first coming from other cultures, > where Microsoft was happy to sell you another complete version > of Windows if you wanted your computer to talk to you, e.g. > Portuguese (and yet another for Brazilian Portuguese, greedy as > they are). > > Of course, Microsoft has caught up (they are trying since the > mid-90s), but not without some spectacular messups. Remember that > one where (I think it was Windows 95), while trying to automate > the spring DST transition were spotted dithering endlessly between > 2AM and 3AM? > > Unix has had this abstraction always: there's the internal time, > and there's the time shown to the user, which depends on the user. > > There's the error itself, and there's the error message shown to > the user. And so on. > > Cheers I just cd'd to that directory and it looks like there's about 1 GB there. I think it is cool to have all that info and I even configured a linux system for BST so cron would record shows I was interested in from the BBC. It works perfectly when we go from Summer time to standard time in Winter because North America and the UK don't switch at the same time but it all works. I've wished one could just set certain parts of the computer to other times but I can also understand why this could be a problem. By the way, I have never been outside the United States but am an amateur radio operator and learned at a very young age to appreciate those time zones if one wants to know when to listen for interesting things. Martin
Fixing a Grub Foul-up, Not There Yet.
I did some duckduckgo-ing about grub rescue and found useful things but am still dead in the water. I appear to be using grub, not grub2. One of the articles I found had an example of how to use grub rescue that all works except, of course, for the actual booting of the kernel. There's an extra little wrinkle in that, as a computer warier who happens to be blind, grub isn't really accessible in that you can not get direct access to it via a serial port and terminal, say, from another computer that is actually working. A really clumsy work-around does work off of the dead computer in that it is old enough that the Print-screen key dumps an ASCII character dump of the screen to the parallel printer output every time you press Print-screen. I found out after connecting a second computer to a parallel-to-serial converter that I was in grub rescue> mode. Each time one types on a keyboard attached to the dead computer, one then must hit Print-screen to find out whether it goes or blows. This is slow and awkward because there is no character-by-character feedback so if you hit the n instead of the m, you don't find out that it's a no go until you read the whole screen. Also the Tabs you hit don't show up in the output so it'salloneunbrokenline. Is there a way I can write the commands in to a text file that I can call to at least know what commands I am executing in grub rescue and do in a tenth of a second what it takes minutes to do otherwise? What I have right now is a text file called stuffcommands and it is sitting in the boot level of the dead boot disk. When I had the drive mounted on a working system, I did chmod +x stuffcommands but since there are no shells running, I just put the following lines in the file. Everyone of these commands works when typed in except for the final one which boots the kernel. What I need to type in with, of course, no mistakes looks like: set root=(hd0,1) linux (hd0,1)/boot/vmlinuz-4.19.0-5-686-pae root=/dev/sda1 #I have yet to see this one work. initrd (hd0,1)/boot/initrd.img-4.19.0-5-686-pae boot Here is a screen capture of what pressing Print-screen produces The first line is that error message and is probably the clue as to what went wrong. The successful commands were laboriously typed in by hand once again to prove they work although by now, I know the kernel version number about as well as my last name. error: symbol `grub_calloc' not found. That's the smoke that the booster is going to blow up on the launch pad. Entering rescue mode... grub rescue> ls (hd0) (hd0,msdos5) (hd0,msdos1) (fd0) (fd1) The root partition is Partition #1. grub rescue> (hd0,1)/boot/stuffcommands Unknown command `(hd0,1)/boot/stuffcommands'. Ah, if only. Those few lines would make each retry so much more efficient. grub rescue> set root=/de/sda1 It worked. grub rescue> linux(hd0,1)/boot/mlinuz-4.19.0-5-686-paeroot=/de/sda1 And that one worked! grub rescue> That much works and it would be so nice not to have to repeat those steps every time. Is there a way to call that stuffcommands text file so that grub thinks it's coming from the keyboard? I think I'd like a keyboard that one can store commands like this in so as to keep the donkey work down to the problem lines. Actually, if only grub could be made to operate remotely, I'd just script all the stuff that works and also know if I fat-fingered anything when it happens so one could backspace and fix it the way we fix any typing error. Before I retired in 2015, I occasionally had to setup new servers and these had lights-out minicomputers that helped one remotely access even a powered-down box in another state, province or country. The linux kernel, itself can easily be configured to be accessible via a serial port or on the local console so grub sorely needs headless capabilities for those rare times where stuff just doesn't come back from a reboot. I appreciate the good suggestions I have gotten from several of you so far. Martin McCormick
Re: Fixing a Grub Foul-up
Dan Ritter writes:
> Here's what you can do:
>
> On a good system, mount your drive. Let's pretend that it's
> recognized as /dev/sdg, and you have a /boot on /dev/sdg1 and
> a root partition on /dev/sdg2.
>
> ls -al /dev/disk/by-partuuid/| grep sdg
>
> will get you the partition UUIDs for that disk. One of them will
> be for /dev/sdg1 and another for /dev/sdg2.
>
> The kernel really likes these as root filesystems identifiers.
> The kernel parameter that you put in /etc/default/grub is
>
> ROOT=PARTUUID=dddf0dd6-dd6b-d542-9eac-015a765cd6f6
>
> although you will want to substitute in the appropriate
> part-uuid for /dev/sdg2.
>
> Finally, you can run
>
> grub-install /dev/sdg
>
> to get a new copy of grub into the master boot sector of the
> disk.
>
> Hope that helps,
It certainly does!
First, thanks to all who answered so far. I think you have
perfectly described what is causing the problem although grub is
not high in my knowledge base like it probably should be.
When I read /boot/grub/grub.cfg, I see
references to a uuid that isn't any of the partitions that have
UUID's. On my disk, Partition 1 is / and blkid spits out a
number that starts with 9F. Partition 2 was created to get an
extended partition of 5 which is swap space so 1 and 5 have
UUID's. The UUID referenced in grub.cfg starts with 3.
The rest of this message consists
of grub.cfg.
Martin
#
# DO NOT EDIT THIS FILE
#
# It is automatically generated by grub-mkconfig using templates
# from /etc/grub.d and settings from /etc/default/grub
#
### BEGIN /etc/grub.d/00_header ###
if [ -s $prefix/grubenv ]; then
set have_grubenv=true
load_env
fi
if [ "${next_entry}" ] ; then
set default="${next_entry}"
set next_entry=
save_env next_entry
set boot_once=true
else
set default="0"
fi
if [ x"${feature_menuentry_id}" = xy ]; then
menuentry_id_option="--id"
else
menuentry_id_option=""
fi
export menuentry_id_option
if [ "${prev_saved_entry}" ]; then
set saved_entry="${prev_saved_entry}"
save_env saved_entry
set prev_saved_entry=
save_env prev_saved_entry
set boot_once=true
fi
function savedefault {
if [ -z "${boot_once}" ]; then
saved_entry="${chosen}"
save_env saved_entry
fi
}
function load_video {
if [ x$feature_all_video_module = xy ]; then
insmod all_video
else
insmod efi_gop
insmod efi_uga
insmod ieee1275_fb
insmod vbe
insmod vga
insmod video_bochs
insmod video_cirrus
fi
}
serial --speed=115200 --unit=1 --word=8 --parity=no --stop=1
terminal_input serial
terminal_output serial
if [ "${recordfail}" = 1 ] ; then
set timeout=30
else
if [ x$feature_timeout_style = xy ] ; then
set timeout_style=menu
set timeout=5
# Fallback normal timeout code in case the timeout_style feature is
# unavailable.
else
set timeout=5
fi
fi
play 480 440 1
### END /etc/grub.d/00_header ###
### BEGIN /etc/grub.d/05_debian_theme ###
set menu_color_normal=cyan/blue
set menu_color_highlight=white/blue
### END /etc/grub.d/05_debian_theme ###
### BEGIN /etc/grub.d/10_linux ###
function gfxmode {
set gfxpayload="${1}"
}
set linux_gfx_mode=
export linux_gfx_mode
menuentry 'Debian GNU/Linux' --class debian --class gnu-linux --class gnu
--class os $menuentry_id_option
'gnulinux-simple-3584c851-6616-464f-8a8e-2d634fca5969' {
load_video
insmod gzio
if [ x$grub_platform = xxen ]; then insmod xzio; insmod lzopio; fi
insmod part_msdos
insmod ext2
set root='hd1,msdos1'
if [ x$feature_platform_search_hint = xy ]; then
search --no-floppy --fs-uuid --set=root --hint-bios=hd1,msdos1
--hint-efi=hd1,msdos1 --hint-baremetal=ahci1,msdos1
3584c851-6616-464f-8a8e-2d634fca5969
else
search --no-floppy --fs-uuid --set=root
3584c851-6616-464f-8a8e-2d634fca5969
fi
echo'Loading Linux 4.19.0-5-686-pae ...'
linux /boot/vmlinuz-4.19.0-5-686-pae
root=UUID=3584c851-6616-464f-8a8e-2d634fca5969 ro console=tty0
console=ttyS0,115200n8 quiet
echo'Loading initial ramdisk ...'
initrd /boot/initrd.img-4.19.0-5-686-pae
}
submenu 'Advanced options for Debian GNU/Linux' $menuentry_id_option
'gnulinux-advanced-3584c851-6616-464f-8a8e-2d634fca5969' {
menuentry 'Debian GNU/Linux, with Linux 4.19.0-5-686-pae' --class
debian --class gnu-linux --class gnu --class os $menuentry_id_option
'gnulinux-4.19.0-5-686-pae-advanced-3584c851-6616-464f-8a8e-2d634fca5969' {
load_video
insmod gzio
if [ x$grub_platform = xxen ]; then insmod xzio; insmod lzopio;
fi
insmod part_msdos
insmod ext2
set root='hd1,msdos1'
if [ x$feature_platform_search_hint = xy ]; then
search --no-floppy --fs-uuid --set=root
--hint-bios=hd1,msdos1 --hint-efi=hd1,msdos1 --hint-baremetal=ahci1,msdos1
3584c851-6616-464f-8a8e-2d634fca5969
Fixing a Grub Foul-up
I have goofed, I think. There is a serca-2000-vintage Dell Optiplex that has been working fine up to yesterday when I did the usual apt-get update followed by the apt-get upgrade on buster. The update and upgrade appeared to work. One of the things that got visited was grub and it was then that I was reminded that there was another drive in the system that had a bootable image of buster on it also. Grub reported seeing it on /dev/sdc which is coorrect. This particular system has a zip drive that always shows up as /dev/sdb so the next hard drive after /dev/sda is /dev/sdc. I rebooted to make sure all was well and waited and waited . . . The system sits there like a bump on a log. I have a usb device that lets one mount IDE and SATA drives that are outside the system so I pulled the sata drive which is the boot drive for the now dead system and plugged it in to the usb converter. the drive breezes through fsck and looks perfectly normal. I looked at /boot/grub/grub.cfg which one is not supposed to edit as grub builds it based on /etc/default/grub which one does edit. If I was to mount that partition on a working system, it, of course, will have a different device number such as /dev/sde1 instead of /dev/sda1 which it should have when booting up the system it normally runs in. Is there a safe way to mount this drive, possibly using chroot, re-run grub-config and get the drive bootable again? If I look at grub.cfg and /etc/default/grub, everything looks as if it should work but it doesn't. I think boot problems are some of the most agrevating issues. They are true show stoppers. I've got backups but that's beside the point. Unless I can fix whatever happened, it's going to be quite a time waster. Thanks for any constructive suggestions. Martin McCormick
Re: Newbie
=?euc-kr?b?yLK6tMjx?= writes: > Hi Arun, > > Yes this is question place. > > Sincerely, Byung-Hee > It is one of the most helpful groups I know of as sometimes, there are questions that don't lend themselves to a search engine string although one can get really lucky if you try to not use words that easily can mean several things at once. Occasionally, we dazzle ourselves with our own brilliance, thinking our search terms should be so concise as to drill right down through all the Ebay pitches and mercantile flotsam to see the answer to our question on the first link to pop up only to find we have asked a question similar to "Can birds fly?" When my wife was getting her Master's in library science, she related a story about a person walking in to a library and asking that question. It turned out that the patron was interested in whether or not birds could be carried on an airplane and how do you do this? The search engines are as good as we are so if you ask duckduckgo if birds can fly and also ask Google the same question, you probably won't get quality answers from either search but with one of the two, your spam level won't change. Three guesses as to which engine changes your spam quantity. I do amaze myself at how many searches go off the tracks because there are many ways to interpret the same question and, when you see what you got, one can usually also see why. If you like puns, you may be thinking like a search engine. For those not familiar with English, a pun is a play on words in which one word has many different meanings. The punster intends for you to notice the other meaning. If you have questions about debian buster or redhat or freebsd, it cuts through a lot of jungle if you put the operating system you are asking about as the first word so that something like debian buster end of line character will instantly weed out how Windows does it as an example. If it doesn't completely remove all the irrelevant info, the unwanted things tend to be near the bottom of your search. Martin
Re: Looping Shell Scripts and System Load
Greg Wooledge writes: > All-caps names are reserved for environment variables (HOME, PATH), > and internal shell variables (IFS, PWD, HISTFILE). > > Avoiding all-caps names allows you to avoid collisions with a variable > name that might be used for something else. Most of the time. This > being the Unix shell, there are *always* stupid exceptions (http_proxy > and friends on the environment side, and auto_resume and histchars in > bash). Thank you. I learned something today that I didn't expect to learn which is why I posted the question in the first place. I just wasn't thinking, I guess and used the all-caps names to indicate that they stood for files. If one collided with an environment variable name, it could make the script fail in strange ways that would be totally unpredictable, depending on which variable one preempted. Martin
Looping Shell Scripts and System Load
I wrote a shell script that unzips documents and I originally
wrote it such that it gets document #1, unzips it then gets
document #2, etc and it does that just fine so I wondered if I
could make it run faster by starting several processes at once,
each one unzipping a file. It's certainly still running and will
eventually finish but I created a monster because it starts as
many processes as there are items to unzip.
#!/bin/sh
unarchive () {
unzip $1
return 0
}
MEDIADIR=`pwd`
mountpoint /mags >/dev/null ||mount /mags
mountpoint /mags >/dev/null || exit 1
cd /mags
#rm -r -f *
for MEDIAFILE in `ls $MEDIADIR/*`; do
dirname=`basename $MEDIAFILE`
mkdir $dirname
cd $dirname
unarchive $MEDIAFILE &
cd ../
done
wait
cd ~
umount /mags
exit 0
If there are 3 zipped files, it's probably going to be ok
and start 3 unzip processes. This directory had 13 zip files and
the first 2 or 3 roared to life and then things slowed down as
they all tried to run.
I expected this and I've been doing unix shell scripts
for literally 31 years this Summer so it is no mystery as each
new job spawns a whole new set of processes to unzip the file it
is working on while all the others are still grinding on.
Miscreants have been known to deliberately create
loops that keep starting processes until the system crashes.
Fortunately, this is one of my systems but this made me
wonder before I reinvent the wheel if there is a way to make a
shell script throttle itself based on current load so it keeps
slurping resources until the next iteration starts too many and
things start to bog down. When some of the earlier or shorter
processes finish, the loop can restart and start some more unzips
until all are done.
Right now, uptime looks like:
11:48:07 up 26 days, 23:10, 7 users, load average: 16.15, 15.60, 10.65
That's pretty loaded so ideally, one could start the
looping script and it would fire up processes until things got
really busy and then not allow any more new procs to start until
some have stopped so cron and other system utilities don't stop
running which is what happens when systems get too busy.
Thanks for any constructive suggestions.
Martin McCormick WB5AGZ
Re: What Needs to be Done here?
Andrei POPESCU writes: > apt(-get) is informing you that a configured repository has changed one > of its values (in this case the 'Version', but could be any other > field). This is to provide a safeguard against repositories changing > values behind your back, possibly with security consequences. > > Just imagine a malicious (or just incompetent) third-party repository > suddenly claiming to be "buster-security" on a system configured to > install security updates automatically. It makes perfect sense to me. Thanks to all who responded and the fix worked as previously stated. Martin McCormick
What Needs to be Done here?
$sudo apt-get update [sudo] password for martin: Get:1 http://security.debian.org buster/updates InRelease [65.4 kB] Get:2 http://ftp.us.debian.org/debian buster InRelease [121 kB] Get:3 http://ftp.us.debian.org/debian buster-updates InRelease [49.3 kB] Get:4 http://security.debian.org buster/updates/main i386 Packages [201 kB] Get:5 http://security.debian.org buster/updates/main Translation-en [109 kB] Get:6 http://ftp.us.debian.org/debian buster/main i386 Packages [7,862 kB] Get:7 http://ftp.us.debian.org/debian buster/main Translation-en [5,969 kB] Get:8 http://ftp.us.debian.org/debian buster-updates/main i386 Packages [7,380 B ] Get:9 http://ftp.us.debian.org/debian buster-updates/main Translation-en [5,166 B] Fetched 14.4 MB in 54s (267 kB/s) Reading package lists... Done N: Repository 'http://ftp.us.debian.org/debian buster InRelease' changed its 'Ve rsion' value from '10.0' to '10.4' I think I saw this once before but don't remember how to make it good. Thanks Martin McCormick
Re: Output from date command defaults to 12-hour in Buster.
Greg Wooledge writes: > It's an intentional change. It's a "feature" from the libc developers' > point of view. As far as they are concerned, Americans use 12-hour > clocks, so the en_US.utf8 locale is supposed to present times in 12-hour > format by default. This American is an amateur radio operator and before that was a short wave listener since the age of around eleven and grew to like the 24-hour clock since any given time occurs exactly once per day. One day, at work several years ago, I saw an outage announcement for one of our departments for a service and started to heat up under the collar because the outage was going to be between 11:00 and 12:30 or something like that but the thermal rise around the neck line soon cooled when I realized that it was PM and AM so nothing terrible was about to happen as this would have been cause for mutiny if it was the middle of the day. > > The fact that many of us *don't* want times shown in that format is a > preference, so it falls on us to configure our own environments according > to our own tastes. That's fine now that I know what is really happening and everybody can go home happy. I remember grousing to a coworker of mine as to when would we start telling time like grownups around here,bla,bla,bla and her response was, "If you think we're going to start using military time, it's never going to happen. She, by the way, wasn't involved with the outage so we were just having a conversation and I was glad I caught the AM and PM parts before making a fool of myself which is easily done. Martin
Re: Output from date command defaults to 12-hour in Buster.
Greg Wooledge writes: > On Tue, Apr 28, 2020 at 10:53:25PM -0600, Charles Curley wrote: > > Adding > > > > alias date='date +"%a %b %d %T %Z %Y"' > > > > to one's .bashrc or /etc/bashrc should get the OP what he wants. It did make just the date command work as desired. I actually tried that very thing maybe a year or so ago and it worked, sort of. Greg Wooledge continues: > No, this is not a viable solution. It will completely hinder your > ability to use date with other format arguments, and it will not > address the underlying problem, which is in the locale definition used > by strftime(3) and similar pieces of libc. (There are other programs > that are affected by this, not just date(1).) > > Setting LC_TIME=C is a much better answer. I do appreciate the help. I remember setting up the alias, cheering when the date command worked, and then about 10 or 15 seconds later, swearing when something else, I forget what, filled the screen with a cacophony of error messages and I immediately realized why and put things back the way they had been. Martin
Re: Output from date command defaults to 12-hour in Buster.
Reco writes: > Hi. > If you need it systemwide, consider doing this (will require relogin, at > least): > echo 'LC_TIME=C' >> /etc/default/locale That was what I needed. /etc/default/locale did not contain that line but did contain # File generated by update-locale LANG="en_US.UTF-8" > > If you need it for your user only (will require a new terminal emulator), > > echo 'LC_TIME=C' >> ~/.bashrc Many thanks to all who responded. I had thought all along that I was dealing with a feature rather than a bug because one of the beautiful things about the philosophy of unix-like operating systems is that new capabilities tend to layer on top of older behaviors so one can enjoy the best of all worlds when it is practical and safe to have this capability. My first thought after making the change was that it had had no effect but I was not completely logging out. I run the screen utility and so I stopped screen but was still logged in. After getting down to the login prompt, logging in with the usual username and password, not only did this installation work but I happen to be running 2 other installations of buster on other old PC's and since the environment variable is exported with each new screen window, their responses to the date command magically fixed themselves. Martin
Output from date command defaults to 12-hour in Buster.
In every flavor of unix I have used since I began learning unix in 1989, the date command would produce a string containing the current time in 24-hour format similar to Tue Apr 28 20:25:11 CDT 2020 If you run the date command in buster, you get Tue 28 Apr 2020 08:26:24 PM CDT One can cause date to run in 24-hour format but you have to run date as follows: date +"%a %b %d %T %Z %Y" Some people have set their locale to British English and now get the older-style 24-hour date format but setting the locale is kind of an extreme way to do things. Is there any environment variable or local configuration variable which will make date produce the 24-hour time stamp similar to past implementations of date? Martin McCormick
Re: Microcom; What's this Script Feature?
I will reply to both excellent responses. Thank you.
Dan Ritter writes:
> Time to learn the awesome power of Linux.
>
> Three ways to do this:
>
> 1. shell script
>
> Create a text file with the following two lines of code:
>
> #!/bin/sh
> exec microcom -f -p/dev/ttyUSB4 -s9600
>
> Name it something short and memorable, like serial
>
> Then
>
> chmod a+rx serial
>
> And from then on, it's a program you can run.
>
> 2. shell alias
>
> Most shells have aliases available. In bash, you can stick them
> in your .bashrc file. Add this line:
>
> alias serial='microcom -f -p/dev/ttyUSB4 -s9600'
>
> and then re-evaluate your .bashrc (which is done automatically
> on login):
>
> . .bashrc
>
> Now you have a new command.
>
> 3. shell function
>
> Most shells have functions available, too. The difference
> between an alias and a function is that an alias is just a
> substitution, but a function can take arguments and perform
> complicated feats of logic. In this case, a function is
> overkill, but it's still easy to drop in to your .bashrc.
>
> function serial {
> microcom -f -p/dev/ttyUSB4 -s9600
> }
>
>
> There you go.
Reco writes:
> Hi.
>
> Judging from the source it it should open a text file on your side (i.e.
> "x filename") and feed its contents line by line to the other side.
> So whatever you'll write in the file is specific to the device you're
> connecting to.
>
> Reco
I could have done a better job of frasing my question as
I love the power of unix and use shell scripts and aliases
all the time.
What is confusing me about scripts in microcom is the
following situation:
I wanted to output device-specific commands and at least
see the responses much like the send/expect pairs in the expect
utility or the OUTPUT and INPUT commands in kermit scripts.
One starts the script while in the command mode of
microcom and it seems that your script should only contain
commands for microcom such as defining the port, speed, etc,
basically what the help screen says one can do.
It doesn't seem like you can put device-specific commands
in the script file.
I wrote a little script that exited command mode with the
exit command and then typed a command that was meant for the
device and then I typed x ./tester while in command mode.
It ran the "exit" command which put one in the terminal
window. You could type things then and each thing you type went
right to the device. I then removed the exit command and left a
command for the device.
It interpreted that command as being meant for microcom
so did not do anything but respond that it did not understand the
command.
microcom does work with expect but can't see the Carriage
Returns at the end of the lines returned by the device. If you
know how the response should end, expect does see the ASCII
characters and moves on. Otherwise, one must allow a reasonable
time such as 1 second for the timeout.
I was hoping there was some way to duplicate expect or
kermit with just the microcom app but this is not a show stopper
at all. At least there is still a serial terminal that can talk
to devices whose only connection to the outside world is a RS-232
cable.
Again, thanks for everybody's help.
Martin McCormick
Re: Fwd: Serial Port Issues
deloptes writes: > Chris Rhodin wrote: > > > Tonight I'll look at the serial port ioctls and see if I can spot a > > difference there. I also try enabling flow control and fiddling with > the > > signals to see if that unstops it. > > Are you sure that this is enabled in the BIOS, also some serial ports like > HP have special connectors and layouts. > Best would be to look at the manual first. > > I have attached a USB to the server. From there I can log in to the > firewall. I can not use the same port in the opposite direction. > > However it is strange that you do get the connection only in one > direction. > It could be some kind of special connector > > Otherwise I used those to enable the service > > https://wiki.debian.org/systemd#Virtual_and_serial_console_changes > > https://www.thegeekdiary.com/centos-rhel-7-how-to-configure-serial-getty-with-systemd/ > https://wiki.archlinux.org/index.php/Working_with_the_serial_console Another possible fly in the ointment could be a hardware issue. Some RS-232 ports are old-school and aren't happy with any voltage range other than +12 for one state and -12 for the other while there are serial ports that can handle state changes of + or - 3 volts so they safely handle logic-level signals and also can handle the old-school RS-232 levels. Then there are some that handle logic-level signals and would figuratively melt if you hit them with +-12 volts. Martin
Microcom; What's this Script Feature?
While working with Microcom, I tried the "help" feature while in command mode and it works but there doesn't seem to be much other information. Here is a screen shot of a command I sent to a serially-connected two-way radio followed by the Help screen for microcom: I put a * in front of the script command. connected to /dev/ttyUSB4 Escape character: Ctrl-\ Type the escape character to get to the prompt. VF 016250,0,0,0,0,0,0,00,00,000,,0,0 Enter command. Try 'help' for a list of builtin commands -> help speed - set terminal speed exit - exit from command processing flow - set flow control dtr - set dtr value rts - set rts value break - send break quit - quit microcom help - show help * x - execute a script log - log to file # - comment md - Display memory (i.MX specific) mw - write memory (i.MX specific) mwb - write memory byte (i.MX specific) mwh - write memory 2 byte (i.MX specific) upload - upload image (i.MX specific) connect - sync communication to Processor (i.MX specific) sniff - sniff and dissect communication from ATK (i.MX specific) -> Everything seems to work as far as I can tell but what does a script look like? I am sure it's kind of like expect or the old kermit scripts but I haven't yet been able to send anything it liked. The system I have been hacking on sends only carriage returns in it's responses so what one gets on the screen is one long line that gets over-written but that's no mystery. The unix convention of typing the Up-Arrow and starting microcom is very handy since one does not have to type microcom -f -p/dev/ttyUSB4 -s9600 each time. Actually, I usually get away with !mic followed by Enter and it starts. Good work to everybody who created this useful little terminal program. Martin McCormick WB5AGZ since Oct of 1969
Re: I Miss ckermit in Buster.
I installed microcom and like it as it is very similar to the functionality I had with ckermit. I briefly thought of compiling from source but laziness got the better of me and I am happy with microcom. Expect is what I am using for scripting so I just took my kermit scripts and saved the important strings and put those in to an expect script. This is what I love about unix. I have had a little trouble getting the expect scripts to be happy with the output from microcom but when you can exactly define what should be there either literally or via a RE, it works beautifully. For some reason, "\r" and "\n" seem to never match and I even tried "\r\n" and it just times out so the project I was working with is accomplished by setting timeout in expect to 1 second but hopefully I can figure out what is wrong and make it run at it's maximum speed. Martin The Wanderer writes: > On 2020-04-03 at 17:40, elvis wrote: > > > On 3/4/20 11:04 pm, Martin McCormick wrote: > > > >> The only thing that I truly miss after upgrading to buster is that > >> the package known as ckermit has fallen beside the road. > >> > >> I had a hard-drive fail on one system so installed buster from > >> installation media and the ckermit package apparently isn't part of > >> the distribution any more. > > > > Have you tried compiling from source? Just because it wasn't > > packaged, doesn't mean that you can't try installing it yourself... > > does it say why it was dropped anywhere? > > https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=918061 and > https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=921098 are the best > I've found on it. > > Basically, no maintainer activity in years, and multiple RC bugs. > > If there's an upstream active enough that any upstream aspects of the RC > bugs can be addressed, and if someone were to volunteer to maintain it > and fix any packaging-related aspects of the RC bugs, there's probably > no reason this couldn't be reintroduced. Depending on what those bugs > were (I haven't bothered digging for that info), that might be a tall > order, or it might be trivial. > > -- >The Wanderer > > The reasonable man adapts himself to the world; the unreasonable one > persists in trying to adapt the world to himself. Therefore all > progress depends on the unreasonable man. -- George Bernard Shaw > > > <> >
Re: I Miss ckermit in Buster.
Greg Wooledge writes: > On Fri, Apr 03, 2020 at 08:14:12AM -0500, John Hasler wrote: > > Look at gkermit. It's evidently a GPL rewrite of ckermit. Also take a > > look at screen. > > Yeah, I did an "apt-cache search ckermit" too. > > The package description for gkermit says, > > The non-free package ckermit adds connection > establishment, character-set translation and scripting features. > > Looks like that sentence is out of date now. But it's not clear whether > the additional functionality has been merged into gkermit, or is simply > *gone*. I appreciate the responses. It looks like gkermit is just the file transfer which is good that it still exists but I want the stuff that is gone such as scripting and the ability to type things that go out over the serial port and receive anything that comes in without having to write a whole new program each time. John Hasler writes: > look at screen. I use screen all the time and maybe I am missing something but what you get with screen is a new shell in each window, very useful but nothing to do with RS-232 ports. Martin
I Miss ckermit in Buster.
The only thing that I truly miss after upgrading to buster is that the package known as ckermit has fallen beside the road. I had a hard-drive fail on one system so installed buster from installation media and the ckermit package apparently isn't part of the distribution any more. There are 2 other buster systems sitting here that still have kermit because they got their buster upgrades the nice way and didn't commit suicide so if I knew a little more, I could obviously copy the .deb package over to the kermitless system and make things right or could I? I am not really interested in the kermit file transfer protocol although it is always possible one might need it but the kermit VTxx terminal emulator made it easy to talk to and receive from a RS-232 port. One thing one could do with ckermit was write rather clunky scripts that could mechanize RS-232 communications if you needed to do that. Basically, what is the best way in command-line mode to deal with serial comm ports these days? Thanks. Martin McCormick
Re: Things Kids Shouldn't Do at Home
My thanks to all those who theorise that it was this particular
drive's time to die. It is several years old and I was thinking
along the lines that the rest of you were thinking. One thing I
haven't done yet is to see if the clock crystal that drives the
internal usb controller is still active. I am not sure what
frequency it should free run on but one can sometimes hear the
clock on a general-coverage short wave radio receiver or
scanner-type receiver.
What one hears is a signal that usually sounds like a
continuous carrier with no modulation. It's there when the drive
is powered up and goes away when the drive is disconnected.
Thanks.
Martin
WB5AGZ
local10 writes:
On 2020-04-01 18:07, Martin McCormick wrote:
>
> >> Out of curiosity, I wondered what might happen if I had
> >> two thumb drives containing the same UUID.
> >>
>
> Nothing bad really unless the system is supposed to boot from one of them
> and both are present in the system at boot time.
>
> I have two HDDs (main one and backup one) where partitions on the backup
> HDD have the same UUIDs as partitions on the main HDD. This was done on
> purpose to simplify backups and to have backup HDD to be readily
> available to replace the main HDD. I copied data between the two of them
> many times without any issues whatsoever.
>
> If necessary, you can change UUID with tune2fs:
> # tune2fs /dev/{device} -U {uuid}
>
> Regards,
>
>
Things Kids Shouldn't Do at Home
I have killed an 8 GB thumb drive while doing an experiment.
I had 2 8 GB PNY drives. One has a FAT 32 file system
and the other had no partitions on it as I had deleted the ones
that were there.
The good drive had it's UUID tagged to mount on a
directory I called /flash. The fstab entry is
UUID="3453-A839" /flash vfat rw,user,noauto 0 0
#UUID="5A0D-76AA" /flash vfat rw,user,noauto 0 0
I decided to make a full copy of the good drive to an
identical PNY 8 GB drive which was the one with all the
partitions deleted.
The good drive was /dev/sde and the soon to be murdered
drive was /dev/sdd so my copy command was:
dd if=/dev/sde of=/dev/sdd
It worked and I now had two drives with the same UUID.
I mounted the doomed drive as /flash and did a rm -r
/flash/* so now I had an empty drive whose UUID is the same as
the good drive.
Out of curiosity, I wondered what might happen if I had
two thumb drives containing the same UUID.
After plugging both in to a usb extender, the good drive
is still good. That's the one whose files I did not delete.
The drive I killed now does not register anything at all.
It's as if nothing had been plugged in to any USB port. I
plugged it in to another debian system that didn't witness any of
what I had just done and absolutely nothing happened there
either.
There is no data emergency here, but what on Earth did I
do to the empty drive to make it not even show an error in
syslog?
I am sure that having two devices with the same UUID is
not good, but I expected some sort of error message, not a total
destruction of one of the two drives.
The now dead drive was behaving normally until I plugged
them both in at once.
I was going to do a mount /flash and see what the system
did but it appears that just having both drives plugged in was
sufficient to draw some blood, so to speak, somewhere.
The good drive contains some ebooks and I was planning
to put different ebooks on the dead drive but that is not going
to happen unless I can make the dead drive show up again.
Are there any open-source rescue programs in Linux that
one can run to mess with the on-board controller of the thumb
drive? This obviously killed the target drive since it was
working right up to when it stopped working.
Thanks.
Martin McCormick
WB5AGZ
Re: Running virtual systems
I ran Freebsd as a virtual system on a Mac Pro at work for a year or so (I don't remember exactly how long) and it worked very well with vbox until one day when Apple updated MacOS and poof! my vm died. The only problem I had before that was one most people wouldn't have in that the low-level setup of the VM sent it's output in video rather than text so anyone who uses a screen reader can't rescue it easily if it gets in to trouble at that point. As soon as the VM boots, the output you would see on a console or serial terminal appears in the host's output and one can run it normally from there. The one lesson is Linux or FreeBSD is probably a better host platform because stuff that works under either of those two OS's tends to stay longer and isn't apt to fall casualty to commercial whims. I still mostly like MacOS and even Windows these days but having the machine my mail was on just suddenly vaporize without any warning soured me a bit and I never put another VM on that Mac. Martin David Christensen writes: > I typically enable all CPU virtualization features in CMOS Setup, and > assume the various virtualization solutions will make use of them. > > > > I use FreeBSD and jails for 24x7 services (CVS and Samba). > > > > I have used VirtualBox on Debian Xfce and macOS hosts over the past > several > years. The GUI manager is convenient for a few VM's, but would be a > problem > for many VM's. I recall setting up headless VM's for services, but for get > the details. I ran a Debian Xfce graphical desktop VM in VirtualBox on > macOS for nearly a year, but key mapping/ binding was a constant nuisance > and graphics was adversely impacted (especially multimedia). Graphical > desktop environments, such as Xfce and Windows, are best installed > directly > on hardware. Be sure to pick hardware for which Windows 10 is actively > supported by the manufacturer. > > > > David > >
Re: Using a Debian Live image to Invoke a Rescue Shell
Andrei POPESCU writes: > From memory, I'm aware of two methods: > > 1. Any time after starting the installer, press Ctrl+F2 and there will > be a prompt to press Enter to enable the console. Ctrl+F1 returns to the > installer. > > If using the graphical installer you will need Ctrl+Alt+F2 and Ctrl+F5 > will should get you back to the installer. > > 2. Start the installer in "rescue mode". After doing some basic > configuration it will ask you about the root and will offer to start a > shell. For your purposes chose "open a shell in the installer > environment", because you don't want to touch your system. > > As mentioned above, this is all from memory, it's been a while since I > used the installer. The Control-F2 did it although there was no prompt, at least I didn't hear one. The console showed a shell prompt and I started poking around. This was the buster image and the only disappointment was no fdisk. I found /dev/sda, /dev/sdb and, after plugging in the 1 TB target drive, /dev/sdc. As a card-carrying coward, I made sure that /dev/sdc was the device that wasn't there just a few seconds ago and is here now. This particular PC is of the HP Pavilion family and I was surprised to find 2 hard drives in a stack as Windows is on a single 1 TB logical drive. One would have had to disassemble the system to be able to see the drives and since this is a fairly new system as of February, 2019, it seemed prudent to take as little apart as possible. My heart sank when I saw /dev/sda and /dev/sdb. If this is some sort of software raid, it might be that /dev/sda and /dev/db would be parts of the system and using dd from sda to sdc would yield a useless dump of stuff that only would be useful if you also dumped /dev/sdb and then used some software to combine them back to 1 drive, but read on. I dumped /dev/sda to /dev/sdc dd if=/dev/sda of=/dev/sdc After a deep breath, I hit Enter. The dump started at about 4:30 PM and was still churning along at 9:30 last night. When I checked on it a bit after 05:00 this morning, it had stopped, showing the same number of records in and out and no squawks. There are 5 partitions in the image and it looks like Partition 3 is the user work space. After setting the debian system to be able to mount ntfs, it mounts read-only with some complaints about it being uncleanly mounted but one does appear to be able to read everything. So, What was /dev/sdb? It's a linux image put there by the installer, I guess to use as a virtual disk when one installs it to a new system. Since I don't have another 1 TB drive, I put a 128-GB drive in and after dd if=/dev/sdb of=/dev/sdc as /dev/sdc was now the 128-GB drive, I got a finish after a few minutes. Mounting that drive, I saw the Linux image and the README.txt file said what it was. I am so thankful for the fact that many linux images can be made to boot with the screen reader able to work as I was able to do all of this without needing anybody to look at the screen. The tinkering environment in Windows is still not anywhere near as solid as it is in unix. About the only thing these days that is still inaccessible on most computers that aren't enterprise servers, etc, is the BIOS setup and selection of boot sources. That's still back in the stone age. Many thanks to everyone who helped with information. Martin
Re: usb Confusion
Things are much better here. Tech Support at Crucial insisted that every drive they ship out contains 1 usb-C to usb-C cable and an adapter to make it fit a usb-A port. I figure it had accidentally been discarded as trash or was really left out but I kept looking and found the little box the drive came in. There is a small pocket in the tray containing a pamflet that one suddenly realizes is too deep to be just the booklet. Everything was there and I do believe that is the first usb-C cable I have ever encountered. Again, thanks for clearing up the confusion. Martin McCormick
Re: usb Confusion
Dan Ritter writes: > If I recall correctly, Martin doesn't see well, which explains a > chunk of the confusion here. Well, my wife has excellent vision and we were talking about how pictures can be almost worthless after a certain point. Several of those small connectors look similar. A Lightning connector is about the same size as a microusb but the microusb has 2 little key ways on one side that insure it can only be put in facing one way. > > Martin: Crucial is probably describing the other end of the > cable they supplied -- assuming they supplied a cable. It might > be proprietary at one end and USB type A at the other. But what > you are describing could also be USB type C at one end. There was nothing in the box except the drive which is the reason for the confusion. I thought the microusb with the 2 key ways was a type C and that's when I learned it wasn't when one of those wouldn't fit either way. > > > What is the correct nomenclature for the most common usb > > connector that has been around for 25 or 30 years and fits the > > vast majority of devices using usb? > > USB type A is rectangular and common on PC ends. > > USB type B is trapezoidal, almost square, and common on printers > and other largish peripherals. That's what I always thought. This makes all the sense in the world. > > USB type B-mini is trapezoidal, very small, and has distinct > indentations on the top left and right sides. It was common for > small peripherals like MP3 players. > > USB type B-micro is flatter than B-mini and does not have > indentations. It is common for cell phones and small > peripherals. > > USB type C is about the size of a lightning connector, rounded > on both sides, and is designed to go in upside down or rightside > up without causing problems. I guess I was confused about the microusb versus the usb-C. I am about to call Crucial Tech Support and get straight on the end that goes in the drive. Anyway, I appreciate the information. Thank you. Martin
usb Confusion
After recently ordering and receiving a new 1 TB external SSD drive, I realized I had no way to connect it. It has a small rectangular slot about 8 MM or a quarter of an inch long. A Mac lightning connector is almost exactly the same size but fortunately doesn't plug in but that's the size of whatever fits. Crucial says it is usb-A . What is the correct nomenclature for the most common usb connector that has been around for 25 or 30 years and fits the vast majority of devices using usb? I'll need a cable that fits the old standard usb port on one end and the disk drive on the other. There's an old saying: "Standards are great. Everybody should have one." Thanks. Martin McCormick
Using a Debian Live image to Invoke a Rescue Shell
I don't know if things have changed or I forgot how to do this but I want to boot in to a Debian image and not install it but invoke a shell so as to clone the hard drive on a Windows machine to an external hard drive. For computer users who are blind, this is a real boon in situations like this because most Linux systems these days can be made to boot talking by striking S when the OS starts to boot. You hear, in English first, "Choose your language." It is, of course, the same setup screen everybody sees so one needs to set language, keyboard and general location to get started. If one wants, they can go through the setup and install the whole works but, in this case, I am doing this because I had a stupid moment and wiped out my Windows home directory after a batch file (shell script) got away from me and zapped every file in my home directory instead of one folder I was trying to zero out. Go ahead and laugh. The idea is to clone the internal drive and then try recovering the deleted files. If something further goes wrong, I've still got all the pieces. I remember doing this same thing a few years ago and there is some way to break out of the setup screen and invoke a bash-like shell in order to run mount/umount and dd. Since I boot it talking, all these applications still talk. After all, it's unix and the speech synthesizer was patched in to standard output right from boot. I don't remember exactly what special key sequence I hit to invoke the shell but need to refresh my memory or learn the new procedure. After learning how to get a relatively new HP Pavilion to boot from a usb device, I think that most all the UFI-bootable images will boot. The one I just tried which did boot is debian-10.2.0-amd64-DVD-1.iso I've also got debian-live-10.2.0-amd64-mate.iso and debian-10.3.0-amd64-netinst.iso The netinst image is only 350 MB while the dvd-1 image is about 4 GB. The mate image is around 2.5 GB. Thanks for any and all constructive suggestions as to how to go from Setup to recovery shell. Martin McCormick
So Far No usb Boot HP Pavillion
Here is the system info: OS Name: Microsoft Windows 10 Home OS Version:10.0.17763 N/A Build 17763 OS Build Type: Multiprocessor Free System Model: HP Pavilion Desktop 590-p0xxx System Type: x64-based PC Processor(s): 1 Processor(s) Installed. [01]: AMD64 Family 23 Model 17 Stepping 0 AuthenticAMD ~1600 Mhz BIOS Version: AMI F.15, 7/24/2018 In order to theoretically make this system boot from a usb port, one must go in to BIOS settings and disable secureboot then change the boot sequence order such that the first boot device is usb/CDROM/floppy followed by the inturnal hard drive. We did all that and, when you do that, the system puts out a code that you enter on next boot, okaying the change. A friend and I did all that and it still works booting Windows, but I want to boot debian in order to mount the hard drive and make a clone to another usb-mounted 1 TB drive because I deleted some files I'd like to get back and better safe than sorry. Fortunately, the drive only had 60 GB out of 1 TB used and the Recycle Bin had not been emptied so it's possible I should get back the 2 or 3 files I really want, the rest being expendable but a clone drive to play with is better than playing with the internal drive. Here is the iso image I got to boot Debian: debian-live-10.2.0-amd64-mate.iso The iso image is about 2.5 GB and I have tried both a 4 and an 8 GB thumb drive, using the command sudo dd if=debian-live-10.2.0-amd64-mate.iso of=/dev/sde Of course the OF= command will vary depending on how many drives are connected to your PC. When starting from power off, the system blows by the usb boot drive like it wasn't there. End of story. The system otherwise still works as before. I did try a bootable CDROM and heard a slight convulsion of activity in the CDR drive but then realized it was a 32-bit version so of course it didn't boot. Any other ideas as to how I can get this project off of high center? It might be interesting to try an old-school CDROM of any of the recent debian versions if I can find an image that fits on a 650-MB disk as I don't have any writable DVD's and am not sure if any of the drives I have can burn a DVD. The image would also need to be for AMD64. Any constructive suggestions are much appreciated. Martin McCormick
debian format usb drive that a Mac likes
If one is on a debian system and formatting a usb drive that will be recognized by a Mac, I know that xfs is usually a good choice for the file system but what type of partition are we supposed to use to enclose that xfs file system? I know if you plug a linux thumb drive in to a Mac, the Mac says it can't read the disk and immediately offers to initialize it for you. Thanks. Martin McCormick
Pub Key Exchange Between Buster and Windows10
It was great news to find out that Windows10 includes an openssh client and server and I got the Windows10 system and one Debian Buster system to communicate via ssh/scp which is all good. The final step of getting them to connect via shared public keys is good from the Windows box to the debian box but not completely the other way around as in debian trying to log in to Windows10. On the Windows box via powershell, I ran ssh-keygen -trsa which gave the usual prompts for a passfrase and produced the usual public and private keys in .ssh so I then copied id_rsa.pub from my .ssh directory on the Linux box to authorized_keys on the Windows box after running it through unix2dos to fix \n. I then ran dos2unix on the new Windows box's .ssh/id_rsa.pub to make it suitable for unix and added it to .ssh/authorized_keys. Both machines have each other's key in .ssh/known_hosts. Here's what happens. Going from Windows to Linux, no password is needed to remotely execute commands on the Linux system. For some reason, right now, if I try to execute Windows commands remotely from the Linux box, I must always enter the password to the Windows box and the command runs so the glass is 75% full. The Win10 box generated an id_rsa.pub key which is 404 bytes long. The id_rsa.pub key I generated back in 2016 on the Linux box is 395 bytes long. Each files is one byte longer in Windows because of the \n convention being 0x0d0a in Windows and 0x0a in unix. Any idea as to why the Windows box doesn't seem to accept the Linux credentials? When I do enter the password, everything runs fine but I would rather not use the password in scripts on one system that are running commands on the other. What I have got right now is usable but not right. Any constructive ideas are appreciated. Thank you Martin McCormick
Re: Easiest Way to forward an email Message from Linux to a Mac
Greg Wooledge writes: > Either you didn't run "apt-get update" first, or your mirror is out of > sync. The current version of dovecot-core in buster is > 1:2.3.4.1-5+deb10u1. Thank you. It was the former. I failed to run apt-get update but I didn't just forget. Ever since I upgraded to buster, I see a line in syslog that goes: Nov 4 06:10:01 wb5agz systemd[1]: Starting Daily apt upgrade and clean activities... Before buster, I would run sudo apt-get update and then sudo apt-get upgrade. I thought the cron job had done this automatically this morning when it ran. After running apt-get update, all was quite well. Martin
Re: Easiest Way to forward an email Message from Linux to a Mac
Bob Weber writes: > Why not create a user on the Linux box to receive such emails and have the > MAC client connect to that user on the Linux box. You might have to > install a pop server (popa3d ... easiest to install and configure) or imac > server (dovecot-imapd ... harder to configure and probably more than you > need) on the Linux box if one isn't installed already. It looked for a bit like this should just work in that I entered: apt-get install dovecot-imapd The following NEW packages will be installed: dovecot-core dovecot-imapd libexttextcat-2.0-0 libexttextcat-data liblua5.3-0 libstemmer0d ssl-cert 0 upgraded, 7 newly installed, 0 to remove and 0 not upgraded. Need to get 5,344 kB/5,750 kB of archives. After this operation, 14.2 MB of additional disk space will be used. Do you want to continue? [Y/n] yes Then the wheels flew off: Err:1 http://ftp.us.debian.org/debian buster/main i386 dovecot-core i386 1:2.3.4 .1-5 404 Not Found [IP: 208.80.154.15 80] Err:2 http://ftp.us.debian.org/debian buster/main i386 dovecot-imapd i386 1:2.3. 4.1-5 404 Not Found [IP: 208.80.154.15 80] E: Failed to fetch http://ftp.us.debian.org/debian/pool/main/d/dovecot/dovecot-c ore_2.3.4.1-5_i386.deb 404 Not Found [IP: 208.80.154.15 80] E: Failed to fetch http://ftp.us.debian.org/debian/pool/main/d/dovecot/dovecot-i mapd_2.3.4.1-5_i386.deb 404 Not Found [IP: 208.80.154.15 80] E: Unable to fetch some archives, maybe run apt-get update or try with --fix-mis sing? I ran the following to be safe: wb5agz martin tmp $ sudo apt-get purge dovecot-imapd Reading package lists... Done Building dependency tree Reading state information... Done Package 'dovecot-imapd' is not installed, so not removed 0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded. At least nothing got partly installed but stuff is obviously not quite right. Is it safe to try that suggestion? Martin
Re: Easiest Way to forward an email Message from Linux to a Mac
Bob Weber writes: > > > Why not create a user on the Linux box to receive such emails and have the > MAC client connect to that user on the Linux box. You might have to > install a pop server (popa3d ... easiest to install and configure) or imac > server (dovecot-imapd ... harder to configure and probably more than you > need) on the Linux box if one isn't installed already. > > > > Your MAC would have to have an email client capable of connecting to a pop > or imac mailbox at the ip of the Linux box or host name in the hosts file > corresponding to the Linux box. Thank you. That is essentially what I am thinking of. I setup a similar setup before I retired. The only difference was that all of the hosts at work had fully-qualified domain names but dovecot worked fine on the Linux box and the mac received any mail I sent without any problem. Martin McCormick
Easiest Way to forward an email Message from Linux to a Mac
Here is the setup. We are on a private vlan as in 192.168.x.x. All local host names are resolved via hosts files. Messages to go to the big wide world must go through Suddenlink's SMTP smarthost and I definitely don't want to break that. On rare occasions, I want to forward an email to the Mac which normally doesn't send or receive emails. What would be the simplest way to "forward" an email from the Linux box to the Mac's mailer? The Mac only needs to be able to receive, not send any email. Thank you Martin WB5AGZ
PrintScreen Key on Older Dell
I have connected a parallel-to-serial converter to a Dell Dimension and am getting output which I can save on another system using kermit. I want to go through the BIOS setup routine while capturing the session. Here is a sample of the opening screen of the BIOS setup Dell Computer Corporation (www.dell.com) Page 1 of 2 Precision WorkStation 210 MT Setup BIOS Version: A07 ³ Time: 21:33:54 Date: Thu Oct 10, 2019 ³ This category sets the time in ³ 24-hour format (hours:minutes: Diskette Drive A: 3.5 inch, 1.44 MB ³ seconds) for the internal clock/ Diskette Drive B: Not Installed ³ calendar. ³ Drives:³ To change the value in a field, Primary Type Cyls Hds Pre LZ Sec Size ³ enter a number or use the left- Drive 0: AutoEIDE Drive 65533 ³ or right-arrow key. Drive 1: None ³ Secondary ³ Changes take effect immediately. Drive 0: None ³ Drive 1: None ³ ³ Reserved Memory: NoneÃÄÄÄ CPU Speed:600 MHz ³ Pentiumø III Processor - 600MHz Num Lock: On ³ CPU ID: 681 Chassis Intrusion: Not Detected ³ Level 2 Cache: 256 KB Integrated Thermal Power-off:Enabled ³ System Memory: 1024 MB SDRAM Video DAC Snoop: Off³Service Tag: H8UD1 ³ ÁÄÄÄ Tab,Shift-Tab change fields³ change values³Alt-P next³Esc exit³Alt-B reboot The printer interface is obviously working even if what comes out is a bit de-formatted but I seem to recall, there may be a key sequence one can hit to cause printscreen to essentially stay in effect and echo a continuous log as one does things such as go through the setup. What you saw was what happens when striking the PrintScrn Key. I tried Control-Printscrn and got nothing. Shift-printscrn just did the same thing as printscrn by itself. Is there anything else I can try? Martin McCormick
gzip and old files Solved.
This exercise was a good training session and was sort of a trip down Memory Lane. I am thankful that floppy disks are mostly history but as long as the hardware is still there, it was good to get useful tools that can on rare occasions, get one out of a jam. One of the things I learned while working with tomsrtbt is that while it is possible to format 1.4 MB floppies to 1.7 megabytes, we must take care to make sure we know we are working with one of the over-stuffed disks. If you use the normal mount command such as mount /media/floppy or some variation of that theme, the OS will try to mount it as a 1.4 MB diskette and the mount will succeed but nothing else will. If you write to such a disk, you'll probably ruin it's contents so if it is a valuable archive of some kind, you will have trashed it. If in doubt, slide the Write-Protect tab so that the hole it covers is open. That way nothing can trigger a write. You can add a device to /dev that makes the drive run on 21 sectors/82 tracks as in #sudo mknod /dev/fd0u1722 b 2 60 #sudo mount /dev/fd0u1722 /media/floppy When you mount it properly, it behaves like all the other possible formats. If you mount a 1.72 disk the wrong way so the system thinks it is 1.4 MB, an empty diskette will show lots of dots . $mount /media/floppy mount: /media/floppy0: WARNING: device write-protected, mounted read-only. $ls /media/floppy .÷÷÷ .÷÷÷ .÷÷÷ .÷÷÷ .÷÷÷ .÷÷÷ .÷÷÷ .÷÷÷ .÷÷÷ .÷÷÷ .÷÷÷ .÷÷÷ .÷÷÷ .÷÷÷ .÷÷÷ .÷÷÷ .÷÷÷ .÷÷÷ .÷÷÷ .÷÷÷ .÷÷÷ .÷÷÷ .÷÷÷ .÷÷÷ .÷÷÷ .÷÷÷ .÷÷÷ .÷÷÷ .÷÷÷ .÷÷÷ .÷÷÷ .÷÷÷ .÷÷÷ .÷÷÷ .÷÷÷ .÷÷÷ .÷÷÷ .÷÷÷ .÷÷÷ .÷÷÷ .÷÷÷ .÷÷÷ .÷÷÷ .÷÷÷ .÷÷÷ .÷÷÷ .÷÷÷ .÷÷÷ $umount /media/floppy That was a 1.7 MB mounted wrongly as 1.4 MB. Here is the same empty diskette mounted correctly. $sudo mount /dev/fd0u1722 /media/floppy mount: /media/floppy0: WARNING: device write-protected, mounted read-only. $ls /media/floppy $df -h /media/floppy Filesystem Size Used Avail Use% Mounted on /dev/fd0u1722 1.7M 0 1.7M 0% /media/floppy0 $exit If the disk is empty, df -h will still show it as 1.7 which is okay but a populated 1.7 MB diskette will lie to you by not showing it's capacity. Here is a full disk mounted wrong. $mount /media/floppy mount: /media/floppy0: WARNING: device write-protected, mounted read-only. $ls /media/floppy boot.b bz2bzImage map rc.custom.gz settings.s $df -h /media/floppy Filesystem Size Used Avail Use% Mounted on /dev/fd0862K 836K 26K 97% /media/floppy0 $exit There was nothing shown for capacity. The rc.custom.gz file that was corrupt was really not corrupt when mounted correctly and writing the modified zip file back to the disk worked perfectly as long as the disk has no bad sectors. Let's see. If I was going to backup the hard drive on my main Linux box, I'd need about 300-thousand of these storage items so I thought I'd put it in a modern perspective. The last floppy backup I did was around 2006 or so and I don't miss not doing them at all, especially now with 512 GB hard drives. If you ever end up recovering any data with floppies, write protect them especially if you are not sure how they were made in the first place. Martin McCormick
gzip and old files Partly Solved
Greg Wooledge writes:
> Sounds unlikely.
>
> > $ gzip -d rc.custom.gz
> >
> > gzip: rc.custom.gz: not in gzip format
>
> Where did you get this file?
tomsrtbt-2.0.103
Here's what happened:
The rc.custom.gz file you posted is 961 bytes long. My
corrupt copy is also 961 bytes long and file describes it as
data.
> What does file(1) say about it?
$ file rc.custom.gz
rc.custom.gz: data
> How about
> gzip --test?
$ gzip --test rc.custom.gz
gzip: rc.custom.gz: not in gzip format
> I think it's more likely that your file is corrupt, than that gzip has
> decided to become incompatible with itself.
Fortunately, this turns out to be correct.
The file you posted unzipped with gzip -d on my system
with no issue at all.
The good file has a checksum of
10349 1
The bad version of the same file's checksum is
13550 1.
I mounted tomsrtbt.raw with
mount -o loop tomsrtbt.raw /mnt
and that rc.custom.gz also has a checksum of
10349 1
The install.s script has one to put a blank floppy in to
the drive and does dd if=tomsrtbt.raw of=/dev/fd0 with a record
count and somehow, that original diskette passed all the tests,
seems to boot right up and let me start a serial console on it
without so much as a single error.
There is enough of this that is enough different from
today's world that I thought things were much worse than they
turned out to be. I am amazed that the corrupted disk worked at
all.
Thanks for clearing up the confusion.
Martin McCormick
gzip and old files
I am trying to unzip rc.custom.gz from tomsrtbt so I can give it a serial console. All you need do is modify /etc/inittab and add a line defining one of the serial ports as a console login. Normally, this is trivial and one should just give the command gzip -d rc.custom.gz and, assuming /etc/inittab becomes accessible, edit it and gzip it back up and replace the old rc.custom.gz with the new one. The problem is that in 2002, gzip apparently worked differently so if you use modern gzip on it, it just complains $ gzip -d rc.custom.gz gzip: rc.custom.gz: not in gzip format I tried tar zxf as some suggested in searches of discussion lists so the problem is most likely related to different libraries used back then compared with ones we have now. For those who may not know, tomsrtbt is a clever bit of obsolete technology that crams an incredible amount of Linux on to a 1.7 MB floppy. That is actually a standard 1.4 MB floppy which is formatted with the sectors squeezed more tightly together, giving you 82 tracks and 21 sectors per track as well as a warning that it could harm your floppy drive although most just work fine without complaint. Is there a reasonable way to uncompress this archive? The documentation written with tomsrtbt contains a line stating, Of course, you have to uncompress rc.custom with gzip -d to edit anything within, but the impression I get is that this command worked back then. He also mentioned all the tools on the disk worked against libc5 so one probably needs a $LOAD_LIBRARY_PATH pointing to a working version of that lib. I got a serial console going on tomsrtbt by booting it up, going in to /etc/inittab and adding a serial tty which one must activate by kill -HUP 1. It worked but I would like to make a disk that just starts that way. Any good ideas are appreciated. If I could find the right rock to turn over, I might find a libc5 to wakeup what's already on the disk. This is certainly not urgent but I feel like this is a good training session if nothing else. Most of the standard unix utilities like ls, mount cd and a bunch more are there and work properly as nearly as I can tell. Martin McCormick
Re: .uvc WebCam Data
Dan Ritter writes:
> fswebcam is a package that captures images from V4L2 devices.
> It's command-line driven and has a few useful features like
> resizing, averaging multiple frames, and skipping early frames
> for devices that take a while to focus. It writes JPEG or PNG.
>
> Remember to make yourself part of the video group.
Oh, yes. Interestingly enough, I am part of that group. I was
going to do that and first did groups martin and, what do you
know, I'm already in the group. How I got there I do not know.
So, here's what has happened and it's all good so far.
After much soul-searching which should precede any outlay
of 400 US Dollars, I bit the bullet and bought an Epiphan
AVIO-HD.
The linux kernel immediately recognized it and then the
fun started.
I finally got fswebcam setup after some fumbling around
an plugged the VGA cable in to the appropriate socket on the
video card.
I captured a picture and sent it to my wife's iPhone and
she said it was just a black screen. I knew it should have
basically been a screen shot of my Linux box since I was logged
in via tty1, I think, but it's the first console anyway.
That was yesterday afternoon when the AVIO arrived so
this morning, I moved the VGA connection to another Linux box
whose VGA card only has one output.
Interestingly, the AVIO-HD generates frames of nothing
even when the VGA cable is disconnected and hanging in space or
lying on the table. The JPG files are about 4 KB in size and
fswebcam says it harvested however many frames one asked for.
I made this discovery the way I discover a lot of stuff,
sort of like oh wow! It makes the same length file plugged in as
it is making with the end of the cable in my hand.
When plugged in to the VGA socket on the other Linux box,
I was encouraged because the size of the captured frames always
showed about 10 K instead of 4 K.
I also downloaded tesseract and several other utilities
such as sane plus a jpg from a site which has sample scans taken
with real cameras and paper pages.
The tesseract utility flawlessly converted the sample jpg
in to ASCII text so I tried that
other Linux box's VGA port. This certainly looks like not much
of anything but I was happy to get it:
Debian GNU/Linux 10 audios tty
audio3 login: [43431.294393] print_req_error: 1/0 error, dev fd0, sector 0
[43431.338633] print_reqerror: 1/0 error, dev fdo, sector 0
I guess I may have stuck a blank disk in to the drive or
something as it looks like it is complaining about being unable
to read the floppy disk. It also may be left over from booting
as the floppy is the first boot source and empty.
I also have a small device that closely resembles an
infant-sized PC tower that I payed a whole Dollar for at a flea
market. The back panel has two usb ports, two RS-232 DB9 ports,
audio jacks, a DB25 printer port , RJ45 Ethernet socket
and a VGA socket just like PC's of 15 or 20
years ago. If you plug headphones in to the Line-out jack, you
get a short beep after pressing the power button. What would
it's VGA jack say?
Acute Network Technologies
ThinCast 5000
I looked that up and it is a client terminal-like device
that is meant as a work station in some institution.
Depending on how many resources it has, one might be able
to load a Linux kernel but I am not holding my breath.
Anyway, I want to thank everybody who supplied helpful
information. The tesseract OCR, so far, exceeds my expectations
of it's ability to decode the VGA text from just 1 frame of
capture. I think I can do BIOS setups, probably much more
slowly, but still it beats wasting other people's time especially
when one runs in to a situation where stuff isn't quite right and
one has to revisit the same task several times before things
shake out correctly. It is also possible to save the screen
shots for posterity which is nice if you haven't done some task
in a year or so and are having to remind yourself what you did.
By the way, the black screen on the first Linux system
was due to the fact that the video card has a VGA socket and
possibly a DVI socket. The video is on the DVI socket most
likely and the VGA socket has no signal, explaining the black
screen of nothing.
Thanks to all!
Martin McCormick
Re: .uvc WebCam Data
Dan Ritter writes: > Martin was just sense-of-wondering at modern technology. I'm > guessing his eventual project will snap frames for OCR on > demand, then send the output through a braille terminal or > a speech synthesizer. Our messages basically crossed due to the time lag here between fetches of mail from our ISP but you said it much better than I did. I have no idea at all what this project is going to look like when it is done but it will be something like what you describe. Snap a picture. Try to evaluate it as quickly as possible. Snap another and soforth. The ideal solution would make the person using it feel like he or she is on a serial console without this layer of complexity and is simply interacting with the screen. The reality is that it will more likely feel like what it is, a work-around that barely solves the problem, better than nothing but not much. If it lets me reconfigure the occasional wayward BIOS on an old system without having to bother my dear wife or a friend, I will call it good enough. If we let perfect kill good enough, nothing ends up getting done. Martin McCormick WB5AGZ I will have been WB5AGZ for 50 years in October.
Re: .uvc WebCam Data
deloptes writes: > I still don't get it how you want to capture and process video to text to > audio - perhaps deduplicate frame content etc. - how many frames per > second > do you want to process, cause I did not get this with the 4Mhz and how it > is relevant. I was thinking your display is running at 60Hz, which is most > common nowdays. This means you have 60 images/sec hmmm how do you > process 60/sec? > I am really wondering. You have actually asked about the only questionI can intelligently answer at this point and I am greatful for that. I was marveling at how fast the analog-to-digital A/D converter has to work. I don't know yet whether I must run at 60 frames per second all the time and simply grab one frame when ready or if I can tell the video extraction application to just take one still picture but I need at least 1 good full screen shot. After getting the shot, I should have a jpg or similar digital image which will look like a freeze frame of the screen. It's not quite useful yet but the OCR engine turns it in to ASCII text. Computer users who are blind either use text-to-speech or text to Braille text applications to finally extract intelligence from the text resulting from the OCR output. This "reading" of the ASCII dump will let the user of the system know what is on the screen. One presses buttons to change a setting and then it's time to take another picture and OCR that to see what one just changed. I really won't need to take more than one picture every couple of seconds as it probably takes that long to process each still and listen to the output. Also, I am hoping to be able to compare the most recent screen grab with the previous grab to see what changed rather than read all the unchanged portions of the screen. Keep in mind that this is not motion video and a blinking cursor is probably the only change over many seconds. Martin
Re: .uvc WebCam Data
Dan Ritter writes: > UVC means USB Video Class. The Video For Linux 2 driver system > should recognize it as a V4L2 device. > > fswebcam is a package that captures images from V4L2 devices. > It's command-line driven and has a few useful features like > resizing, averaging multiple frames, and skipping early frames > for devices that take a while to focus. It writes JPEG or PNG. > > Remember to make yourself part of the video group. > > -dsr- Thank you very much. I started using unix-like OS's 30 years ago in June but the digital video field is new to me so I still have a lot of learning to do. As an electronics and amateur radio enthusiast, I am astounded at how fast that A/D converter has to work along with the Nyquist filtering to properly digitize the video. With North American NTSC color video, the dot clock rate is 3.7945 million plus a few more decimal places per second and PAL along with SECAM are just above 4 MHZ. The A/D converter has to sample at twice that rate to keep Mr. Nyquist from haunting anybody from his grave. Martin McCormick
Re: Raspian ntp manual invocation?
Sven Joachim writes: > Or systemd-timesyncd, which is shipped with systemd since version 213 > and enabled by default in Debian since version 219-1. > > Cheers, >Sven > > I have a Raspberry Pi 2 which was running jessie in 2016 and then I upgraded to stretch in 2018. The Pi runs 24/7 and I've not had a bit of trouble with ntp keeping it to within a second which is about as good as it normally gets on any unix-like system. Martin McCormick
.uvc WebCam Data
I am trying to fit all the pieces together in a project I need to do which is to capture VGA video text screens and turn them in to ASCII text via OCR. The OCR program is meant for people to feed in video from a camera or flat-bed scanner which will process the images and decode text from printed pages. I suspect that the image the OCR program is expecting to see is a raster. The video capture device is an Epifan AVIO-HD video digitizer and one of it's modes is VGA conversion with all video sent in the .uvc or webcam format. The part I don't know yet is what needs to happen to convert .uvc in to something that looks like it came from a digital TV camera or flat-bed scanner? Thanks for any and all constructive ideas. Martin McCormick
Re: Easiest way to do VGA to Text
rhkra...@gmail.com writes: > I know this is off point (because you are not the original poster, who, > iirc, > is blind or partially blind), but, if the only reason to reconfigure the > BIOS > is to set the correct date and time, an alternate would be to boot with > the > wrong time, then use, set the (software) clock to the correct time > (possibly > using the utility that syncs to the atomic clocks in Colorado or > wherever, and > then using that other utility that lets you set the hardware clock from > the > software clock. Raspberry Pi's do exactly what you are describing when they run Linux. They have no running internal clock so when they power up, they can only reference seconds that start from 0 in their timer register. Instead of a big bang, we are talking about a little pop. At some point, the Pi gets a network connection going and goes out to pool.ntp.org where there are thousands of unix boxes all over the world that can give you UTC or coordinated universal time to within a second or so if you use a pool near where you live. Search for pool.ntp.org. Very briefly, servers connected to actual atomic clocks are Stratum 1 servers. You can even become one of those by having your own atomic clock or by using a receiver that can sync to the atomic clocks carried by such systems as GPS. These are incredibly accurate. For the rest of us, not trying to crowd source a radio telescope or do some other task that requires accuracy to umteen decimal places, ntpd can get you there to within a second when configured correctly. Ntpd even has routines that check your clock against all the others and add or delete fractions of seconds so the longer your clock runs, the more accurate it gets to a certain point. If you do have a hardware clock, Linux automatically updates it. If you look at system shutdown messages, that's one of them as processes are being shut off. Martin McCormick WB5AGZ
Re: Easiest way to do VGA to Text
Felix Miata writes: > Are these old Dells continuously connected to power whether booted or not? Yes. > I have a bunch of old Dells. When left unconnected to power, some wear > down the > 2032 coin cell CMOS batteries with unusual haste. Once this happens and > the > battery is replaced, reconfiguring the BIOS is required, unless 100% use > of > defaults proves acceptable, which because of the date and time at least, > for me is > never. I know what you mean. Some time before I retired in 2015, we had a Dell server at work that must have had bad steering diodes somewhere on the mother board because it could drain one of those 2032's in just a few hours. Nobody even knew there was a problem until it was shut down for some length of time and then it would come up wrong. Trying to remember what all happened is a bit difficult now but I seem to remember that one could power it up and it would start immediately for 10 or 15 seconds and then shut off at which time one could press the Start button and it would run with all the defaults. Good servers just remember what power states they were in when last shut down or maybe there is a BIOS setting that you can set to determine this behavior but there is none of this business of running for a few seconds and then going in to shutdown. The department that actually owned the server decided to replace it with a new one and that's the end of that story as far as I can relate. The university would have put the defective server in Surplus and state law required that it be sold at auction at which point, some poor bloak would buy it and make the same discovery we had made.:-) Martin
Re: Easiest way to do VGA to Text
David Christensen writes: > What about using a computer whose CMOS Setup utility is accessible via the > serial port? This article indicates the Dell 2450 is capable: > > > http://tldp.org/HOWTO/Remote-Serial-Console-HOWTO/rhl-biosserial.html > > > David > > Thanks for the information but None of the Dells I have are that model. They are all traditional eyeballs-only style. I even have a card that was manufactured many years ago that replaces the VGA card in a number of PC models but not, of course, the ones I have. I had bought it to use at work and it did work fine in a system there but the card will not physically fit the connector on the one system that has a removable video output card and the others all have VGA integrated in to the mother board. You fight the war withthe weapons you have, not what you wish you had. The other possibility touches on a comment that another poster to this thread mentioned. I do own an iPad which has a commercial OCR program on it that while driving one crazy with it's limitations, can sometimes work quite well. If you use the iPad's rear-facing camera and shoot a photo of the monitor screen, it sometimes produces useful results but it is normally kicking and screaming every step of the way. The OCR program is really meant to photograph pieces of paper under light that doesn't flicker. The monitor screen is a classic CRT which flickers at the frame rate of 60 FPS with no setting to increase exposure time which might solve the problem. I waited until night, clamped the iPad in to a tripod fixture aimed at the CRT and observed that it continuously cycled in and out of error mode due to the flicker. A LCD-type monitor might work much better as they have almost no flicker. This is definitely one of those projects in which one must not let perfect be the enemy of good enough. Thanks for the good ideas. Martin
Re: Easiest way to do VGA to Text
john doe writes: > On 7/30/2019 7:01 PM, Martin McCormick wrote: > > > > I have 4 older PC's that generally work well running > > debian but Right now, 3 of them need varying degrees of attention > > to their BIOS setups as Dell motherboards and possibly other > > brands will occasionally modify their boot sequences for some > > reason and the only way one can boot from a CDROM is to get in to > > the BIOS setup and yank the boot order back to one where the CD > > drive is ahead of the hard drive or put an unbootable hard drive > > in. Six or eight months later, one will suddenly discover that > > the boot sequence has fallen back to the useless one where the > > floppy drive is first, followed by the hard drive followed by the > > CDROM. > > > > Why not "simply" deconnecting the hdd once booted reconnecting it? > Granted, it's clearly not ideal! :) I chuckled when I read your message. Not because there was anything at all wrong with the suggestion but because that was the first thing I tried years ago when I stumbled across the problem. Since the boot drive was disconnected, the computer just gave me that nasty little double high-pitched beep which says the game is over before it even started. It seems that there has to be a drive in place that would boot if only it could. Again many thanks. Martin
Re: 3 phase power (was Re: Wireless home LAN - WiFi vs Bluetooth?
rhkra...@gmail.com writes: > An update | correction | recollection ;-) > > On Tuesday, July 30, 2019 11:34:43 AM rhkra...@gmail.com wrote: > > I have seen diagrams in NEC code books for a different arrangement to > get > > 120 volt 3 phase power, but I don't recall ever actually encountering > that > > in real life. > > Oh, wow, how quickly I forget -- I did encounter systems like that, often > for > lighting in industrial applications, And, further, iirc, we could (and > did) > buy and install florescent light (and maybe HID?) fixtures designed to > work on > 208 volts, which we connected phase to phase in that kind of system. > > Of course, I could be misremembering. > > > In that case, iirc, 120 volt loads are connected from a hot > > tap to the neutral wire (the 4th wire of the 3 phase arrangement), and > you > > get (nominally) 208 volts (RMS) connecting phase to phase. I have seen > > things like motors that were rated like 240 / 208 volts (or something > like > > that). > That's the way I understand it too. One of the buildings we worked in at Oklahoma State University had low-voltage wiring to the light switches. Pressing the On button turned on the overhead light, accompanied by the click of a latching relay. Pressing Off released the relay with another audible click from above. I asked one of the electricians as to why the fancy light switches. The building had 3-phase wiring for the air handlers and the lights were powered phase-to-phase at 208 volts. This would have been dangerous if someone took the plate off of a switch for any reason because every wire would be hot between it and anything else. Martin
