Re: [Dorset] Lets all laugh at me, my tale of woe
Hi, Have to say "Been there, done that," he says typing on a newly built machine less than a month old. Friday: Hmm there's a few SMART errors reported. Oh well they look minor I'll look at them soon. Monday night: "Bob I'm getting I/O errors whenever I try to run a command". Argh! One half of the RAID array looks dead and the other riddled with bad blocks including some of the main support librarys. Oh and the backup is nearly a month old. Power cycle, maybe it just needs a restart. Not even a Grub screen. Goes to read lots of messages on the web about how disk failure in RAID arrays puts stress on the rest and can often cause rapid failures of other members. So seven days later with a brand new machine and base gentoo install I load what I think is the working half of the RAID array into a cradle. Not an electronic sausage, won't even spin up. Not looking forward to relying on that month old backup for recovery I try the other half of the RAID. It buzzes and hums alarmingly and then springs into life. Like a demon I "cp -a" /home and /etc to a safe location on the new system. Within a few hours have the old configuration up and running. Big sigh of relief. I was lucky, but some important lessons and reminders for all. RAID is not a magic wand, you still need regular backups. Once a month or so is not frequent enough for backups. Backup /etc as well as /home. ps. I backup to a separate hard drive that I install in a USB cradle. It is kept separate from the main machine when I am not performing a backup. Avoids the possibilty of formating the wrong drive when doing something tricky. New backup regime two drives on alternate weeks. -- Bob Dunlop -- Next meeting: Bournemouth, Tuesday, 2018-09-04 20:00 Meets, Mailing list, IRC, LinkedIn, ... http://dorset.lug.org.uk/ New thread: mailto:dorset@mailman.lug.org.uk / CHECK IF YOU'RE REPLYING Reporting bugs well: http://goo.gl/4Xue / TO THE LIST OR THE AUTHOR
Re: [Dorset] Lets all laugh at me, my tale of woe
Hi Ralph, > Hi bob, > > > One half of the RAID array looks dead and the other riddled with > > bad blocks including some of the main support librarys. > > Was (is) there a regular scrub happening on the array, e.g. `mdadm > --action=check'? I think some distros have a cron job that does this > regularly for all of md(4)'s arrays. No regular scan. We'd debated it's utility at work and concluded it was rather marginal and I'd just done the same at home. Gentoo doesn't install a cronjob by default. The SMART errors I was seeing where not the hard error indications from the Google report but increases in soft error retries etc. > https://en.wikipedia.org/wiki/S.M.A.R.T.#Accuracy has some interesting > stats from a, now old, Google summary of its large pile of rust. That's quite an old paper (2007) they talk about drives up to 400Gb. More recently (2016) they've published similar but covering SSD drives. https://www.zdnet.com/article/ssd-reliability-in-the-real-world-googles-experience/ Interesting reading. Age of the drive is more important than usage, something we'd observed at work. Don't be tempted to buy "old stock" SSDs, they wear out just sitting on the shelf. Oh if anyone is using SSDs out there, make sure your distro is doing a weekly fstrim or equivalent. Most do. -- Bob Dunlop -- Next meeting: Bournemouth, Tuesday, 2018-09-04 20:00 Meets, Mailing list, IRC, LinkedIn, ... http://dorset.lug.org.uk/ New thread: mailto:dorset@mailman.lug.org.uk / CHECK IF YOU'RE REPLYING Reporting bugs well: http://goo.gl/4Xue / TO THE LIST OR THE AUTHOR
Re: [Dorset] OpenWRT (was Network connectivity issues)
Hi, On Mon, Jan 14 at 05:59, Tim wrote: > > > I am considering putting WRT on my router, have to say that I am > appalled at the level of ability in its standard firmware, ever heard of > a router that can not block a port. > > If anybody has any stories regarding OpenWRT I would interested to hear them I run OpenWRT on a brace of Netgear WNR3500L v1. First time I installed (was running Tomato previously) it "just worked". These days because the routers are 9 years old the official firmware images on the openWRT website don't seem to be updated in a timely manner. So now I compile my own firmware from the GIT sources. It gives me more control on what's installed as well, I want IPv6 etc not silly printer apps which shouldn't be on a firewall in my opinion. Building from GIT was straight forward once I worked out that you have to follow the command ordering in the instructions exactly, don't invent smart shortcuts. I suspect some of the build dependencies ain't quite there breaking the shortcuts. Other good tip is invest in a USB/serial cable (or equivalent for your router) so you can plug into the serial console. Great for when you eventually come up with a firmware combo that doesn't run. Exact details of debug and debricking varies from router to router. -- Bob Dunlop -- Next meeting: BEC, Bournemouth, Tuesday, 2019-02-05 20:00 Check to whom you are replying Meetings, mailing list, IRC, ... http://dorset.lug.org.uk/ New thread, don't hijack: mailto:dorset@mailman.lug.org.uk
Re: [Dorset] ed, vi et al
Hi, On reason you had ed on early machines and Vi on later can be seen by examining the code size of even modern builds. Ignoring common OS libraries you have: ed textdata bss dec hex filename 4350911442248 46901b735 /bin/ed nvi textdata bss dec hex filename 270612048 256 2936572b5 /usr/bin/nvi 442019 18688 144 460851 70833 /usr/lib64/libvi.so.0 430302 176282552 450482 6dfb2 /lib64/libncursesw.so.6 Vim textdata bss dec hex filename 2295413 139160 49392 2483965 25e6fd /usr/bin/vi 150110 141282016 166254 2896e /lib/x86_64-linux-gnu/libtinfo.so.5 So even nvi (Keith Bostic's BSD vi rewrite from the 1990s) is twenty times the core size of ed. Vim then doubles it again. Modern coders pah! I spent my three years at university using ed (well em the "Editor for Mortals" actually. Only a couple of years later was I introduced to vi, which has been my editor of choice ever since (35 years). Spend an awful lot of time in ex mode though. One problem with the Editor for Mortals that caught many. Consider the difference between the action of the command "em file" and "rm file" yet they are just one key position apart. -- Bob Dunlop -- Next meeting: BEC, Bournemouth, Tuesday, 2019-08-06 20:00 Check to whom you are replying Meetings, mailing list, IRC, ... http://dorset.lug.org.uk/ New thread, don't hijack: mailto:dorset@mailman.lug.org.uk
Re: [Dorset] Discovering unfamiliar utilities
On Fri, Jul 05 at 12:14, Patrick Wigmore wrote: > On Thu, 04 Jul 2019 10:37:35 +0100, Bob Dunlop wrote: > > nvi > >textdata bss dec hex filename > > 270612048 256 2936572b5 /usr/bin/nvi > > 442019 18688 144 460851 70833 /usr/lib64/libvi.so.0 > > 430302 176282552 450482 6dfb2 /lib64/libncursesw.so.6 > > This type of output was not something I was familiar with. I can see > that size(1) produces output in this format, given a list of object > files, but what method did you use to produce the list of files, > excluding common operating system libraries? The command was simply "ldd /usr/bin/nvi" which shows the list of object dependencies, then cut and paste library names I'm interested in into the size command. As for how to locate an unknown command I don't know, in my case it's too many years of experience. Since you already know about apropos and it's limitations I can only suggest DuckDuckGo is your friend. Or https://unix.stackexchange.com/search is good for a lot of technical questions. -- Bob Dunlop -- Next meeting: BEC, Bournemouth, Tuesday, 2019-08-06 20:00 Check to whom you are replying Meetings, mailing list, IRC, ... http://dorset.lug.org.uk/ New thread, don't hijack: mailto:dorset@mailman.lug.org.uk
Re: [Dorset] ed, vi et al
Hi, On Thu, Jul 04 at 03:15, Ralph Corderoy wrote: > Hi Bob, > > > On reason you had ed on early machines and Vi on later can be seen by > > examining the code size of even modern builds. > > Right, given the small amount of RAM on early machines, ed fitted where > bigger programs couldn't. IIRC vi or its predecessor caused performance My wife has just reminded me of a couple more reasons for using ed rather than vi. Vi is in /usr/bin so not available until /usr is mounted. Ed would run without a /tmp directory, vi won't. Both are non-problems on modern systems. -- Bob Dunlop -- Next meeting: BEC, Bournemouth, Tuesday, 2019-08-06 20:00 Check to whom you are replying Meetings, mailing list, IRC, ... http://dorset.lug.org.uk/ New thread, don't hijack: mailto:dorset@mailman.lug.org.uk
Re: [Dorset] Strange hard disk
Hi, An idea of which Humax model might have been useful. My Humax Foxsat HDR had a fairly conventional partition table and layout for a linux box. The notes from when I upgraded 300G to 1.5TB said the original was partitioned as follows: /dev/sdb1 2G ext3 /reserve.info 745920 bytesRecording reservation list. /dev/sdb2 99M ext3 /fsatepg/epg.dat4413676 bytes Program guide data. /dev/sdb3 267G ext3 /Movie/ empty /Video/ Video streams /dev/sdb4 25G ext3 /Music/ empty /Photo/ empty I think you need to add the sparse_super and large_file flags when creating the filesystems but otherwise it was standard. Maybe the later models have a reserved boot space that needs to be skipped ? On Wed, Feb 26 at 05:14, PeterMerchant via dorset wrote: > Hi all, On tuesday I hope to remember to bring along a hard disk from my PVR. > it is formatted in a manner that I can't read except with the Humaxrw utility > in windows. If someone has a SATA connection device?? I'll be interested to > see if there is any way you guys can devise to read it. -- Bob Dunlop -- Next meeting: BEC, Bournemouth, Tuesday, 2020-02-04 20:00 Check to whom you are replying Meetings, mailing list, IRC, ... http://dorset.lug.org.uk/ New thread, don't hijack: mailto:dorset@mailman.lug.org.uk
Re: [Dorset] Tracking Down Where Python Modules Come From
Hi, A 16:1 fanout would raise alarm bells in most hardware engineers minds I think. Remember the SCLK and MOSI lines would each be driving 16 devices in parallel, and each peripheral MISO line would have top drive 15 of it's tristated companions. I suspect a few buffers would be required. If the peripherals have input data to supply to the controller then the 16:1 would raise my software concerns as well. Polling 16 devices to get input from just one or two would be inefficient. An 8:1 chip select mux might be a more practical limit. Some SPI controllers even support this style of operation. I think it was the Atmel SAMA5D3 series gave you the choice of three separate chip selects for three devices, or three lines working in concert to drive an external 8:1 mux for eight. No idea if the RPI controllers would do this, it would be deep is the SoC manual, but I doubt it. On Sun, Aug 16 at 01:43, Terry Coles wrote: > On Sunday, 16 August 2020 12:46:53 BST Ralph Corderoy wrote: ... > > Could you demux outputs from the Pi to give more chip-selects lines, > > e.g. four GPIOs could drive one of 2???=16 CS lines. > > https://en.wikipedia.org/wiki/Demux#Digital_demultiplexers > > > It's the demux's outputs which fan off as CS to each SPI device. > > Meanwhile, they all get SCLK, MOSI, RST and D/C straight from the Pi. > > You could leave the software thinking there was only one SPI device and > > drive the demuxer yourself just before each run of SPI-writing for a > > device. If they were different speed devices then you'd have to change > > the bus speed too. > > That's a very good idea (now why did I not think of that? :-) ). I'll look > into it. We can easily do that on a piece of Veroboard and it has the > advantage that the standard library will still work; I just have to assert > the > extra GPIO pin to toggelt the right CS pin. > > > No idea if it would work. This is a hardware problem. :-) > > I'm pretty sure it would. I'll pass it on to my co-volunteer who asked me to > look into this. He was a hardware engineer before he became a company > director. Hey you can be a company director and still keep your day job if you want. I kept up my software work although I did back pedal on the hardware. -- Bob Dunlop -- Next meeting: Online, Jitsi, Tuesday, 2020-09-01 20:00 Check to whom you are replying Meetings, mailing list, IRC, ... http://dorset.lug.org.uk New thread, don't hijack: mailto:dorset@mailman.lug.org.uk
Re: [Dorset] Old Books - Junk?
Amatuer. I've got technical books from 1978 on my shelf, acquired new for use not something I've picked up later for historic interest. Referred to a couple of the Z80 programming ones just last year. Also have two early editions of K&R, had to buy a second when I misplaced the first. As for getting rid of some of them. I've had no luck with charity shops or computing clubs etc. My "The Art of Computer Programming" went in the bin, yet I see the 2011 box set now retails for over a hundred, I should have held on to them. Anybody want a set of X-Windows programming manuals ? Eight volumes 1-7 (6 was in two parts) plus several suppliments. Hah just spotted "Best of Byte Vol 1" (1977) I'm keeping that one. On Wed, Jan 06 at 10:21, PeterMerchant wrote: > If anybody wants them, I will keep them aside, otherwise it's recycling bin > or charity shop. ... -- Bob Dunlop -- Next meeting: Online, Jitsi, Tuesday, 2021-01-05 20:00 Check to whom you are replying Meetings, mailing list, IRC, ... http://dorset.lug.org.uk New thread, don't hijack: mailto:dorset@mailman.lug.org.uk
Re: [Dorset] Raspberry Pi Pico
Hi, > I notice that it doesn't have WiFi, and I wonder if it could be programmed > from the Arduino IDE as 'c' is mentioned. Perhaps that will come. I have been > using a Wemos D1 which has some of these features plus Wifi, and programmed > in c. In my professional work this was often the demarcation line. Need a network Ethernet or WiFi then use a SoC and linux or at least a multitasking OS. Need lowest power and no network, use an MPU and bareback code. Now for hobby use that equates to, networking use the Pi Zero W or better, no networking STM32 blue pill and the like. The Pico even looks like a blue pill. The newer F4 based black pills look comparable to the Pico, single core but it's Cortex-M4 not M0 with hardware floating point and DSP instructions. Similar price from usual suppliers. There's a nice write up here: https://hackaday.com/2021/01/20/blue-pill-vs-black-pill-transitioning-from-stm32f103-to-stm32f411/#more-454155 I suspect the RPi Pico will soon win out just on popular labeling. All have IDEs available that allow you to program them in C these days, although my personal method is Vi + gcc + make. Oh and it's 'C' not 'c' please. -- Bob Dunlop -- Next meeting: Online, Jitsi, Tuesday, 2021-02-02 20:00 Check to whom you are replying Meetings, mailing list, IRC, ... http://dorset.lug.org.uk New thread, don't hijack: mailto:dorset@mailman.lug.org.uk
Re: [Dorset] Cherry CyMotion Master Linux keyboard no longer works properly
Hi, On Wed, May 18 at 07:46, Hamish McIntyre-Bhatty wrote: ... > > Huh, must be some configuration then. Maybe making a copy of /etc on > both machines and then comparing the difference between the files. I'm > not sure if there's some fancy recursive diff command to make that easy, > but Ralph might know :) Well "diff -r -w DIR1 DIR2" usually works well for me. -r is the recursive flag, -w causes diff to ignore white space differences. However comparing two /etc directories is gonna produce a lot of noise changes unless the distros are very closely related. Try to work with smaller sets like the configuration sub directories. -- Bob Dunlop -- Next meeting: Online, Jitsi, Tuesday, 2022-06-07 20:00 Check to whom you are replying Meetings, mailing list, IRC, ... http://dorset.lug.org.uk New thread, don't hijack: mailto:dorset@mailman.lug.org.uk
Re: [Dorset] Electricity power usage
Hi, On Sat, Jul 09 at 12:35, Terry Coles wrote: > On Saturday, 9 July 2022 09:53:31 BST Peter Merchant wrote: > > I borrowed an electricity power meter for a few days and went around the > > house measuring everything. A couple of interesting discoveries: I've been monitoring my whole house consumption with a Current Cost meter for about 12 years now. The meter spits out XML on a serial port which I capture with a script and save the number to a log file. Saved me money a couple of times detecting security lights that stayed on all night etc. Anyway over that period the whole house standby consumption (running fridges etc) has gone from about 500W down to 200W. Some has been down to newer better electronics devices with lower standby modes, an old laser printer used to be 45W in standby the new one is <1W. But the big shift was when our two fridges and the freezer were replaced due to failures. There seems to have been an order of magnitude improvment in fridge/freezer efficiency in the 20 years between the old and the new. So if you have an older device it's worth checking it out. > I have one permanently connected to the tails from my Solar Panels. > > > Total standby power of devices in the house = 28.5 watts This is sort of > > invalid because the monitors on my 2 tower PC's are on a switch that turns > > them off when the PC is off so their standby power is less then. Also the > > meter seemed to register in increments of 0.5 watts. > > When the sun has gone down, my Solar Panels show a consumption of 57 W. I > don't believe for one moment that the panels work at night (it's pretty much > always the same regardless of the level of light for street lights or the > moon), so that is consumption just to keep the inverter alive. I also have solar so a lot of my daytime electric is "free" but I'd check your solar standby consumption numbers. Overnight my solar controller goes to sleep consuming <0.5W, it even turns the Ethernet interface off. When it wakes in the morning as the solar voltage rises it consumes no more than 10W for the few minutes before it fires up the inverter. 57W sounds very wrong. And yeah solar has paid back the investment over the years even if SSE has defaulted on the FITS payments this year. I guess they have financial problems and it easy for them to stitch up the small guys. -- Bob Dunlop -- Next meeting: Online, Jitsi, Tuesday, 2022-08-02 20:00 Check to whom you are replying Meetings, mailing list, IRC, ... http://dorset.lug.org.uk New thread, don't hijack: mailto:dorset@mailman.lug.org.uk
Re: [Dorset] Electricity power usage
Hi again, On Sat, Jul 09 at 02:55, Terry Coles wrote: ... > The Inverter is a Platinum 3800 or 4200 (I think) made by Diehl. There is no > mention of a standby or sleep mode. Since it was installed in 2011, I assume > that the design pre-dates that by some years and perhaps they didn't have > that > feature back then. Ah Google threw up a French datasheet. Nightmode is <2.5W. So I guess it's a measurment issue. Our inverter is a 2015 model, the original 2011 one failed after four years. The installer supplied a newer model under warantee. On a related note I've just about finished converting the house (inside and out) to LED/CFL lighting. Can anyone think of a use for all the old incandescent bulbs or even how they can be recycled? -- Bob Dunlop -- Next meeting: Online, Jitsi, Tuesday, 2022-08-02 20:00 Check to whom you are replying Meetings, mailing list, IRC, ... http://dorset.lug.org.uk New thread, don't hijack: mailto:dorset@mailman.lug.org.uk
Re: [Dorset] New laptop
Hi, On Tue, Sep 20 at 05:26, Peter Merchant wrote: > I wonder if you could ask the group for any suggestions around ,£500. 256 > /512 SSD 8GB memory i3/5 or AMDr3/5, Al chassis, 14"+/- , fingerprint and > backlight UK keyboard. I used PC Specialist [1] for my last laptop a few years back, their front page prices include windows so go into configure and select No OS and watch the price drop. Their Pre-Sales support were most helpful confirming the Ubuntu/Mint would work with every thing and even pointed meot the OEM manual for the underlying hardware. The hardware warantee doesn't evaporate if you open the box either. Never had to call Post- Sales support. Intergrated fingerprint will be the sticking point with linux and many laptops. I've used a Yubico key for 2FA and login with Ubuntu before so what about using the later YubiKey Bio Series with built in scanner. [1] https://www.pcspecialist.co.uk/laptop-series/14/ -- Bob Dunlop -- Next meeting: Online, Jitsi, Tuesday, 2022-09-06 20:00 Check to whom you are replying Meetings, mailing list, IRC, ... http://dorset.lug.org.uk New thread, don't hijack: mailto:dorset@mailman.lug.org.uk
Re: [Dorset] Changed IP address lost NAS, but........
Hi, Have you checked the /etc/exports file on the NAS? It's the list of NFS clients allowed access, mine looks something like this. # /etc/exports: NFS file systems being exported. See exports(5). # /home 192.168.42.162(rw,no_subtree_check,no_root_squash) /home 192.168.42.163(rw,no_subtree_check,no_root_squash) On Sun, Jan 21 at 09:01, Tim wrote: > I have recently changed my Internet Provider and that provider supplied > me with a Linksys Mesh Router with Wifi 6 ... > My line is the fstab file looks like this > > 192.168.18.150:/volume1/Data /media/nas nfs > users,rw,_netdev 0 0 -- Bob Dunlop -- Next meeting: Online, Jitsi, Tuesday, 2024-02-06 20:00 Check to whom you are replying Meetings, mailing list, IRC, ... http://dorset.lug.org.uk New thread, don't hijack: mailto:dorset@mailman.lug.org.uk
Re: [Dorset] Pi 5's PCIe connector for NVMe SSDs.
Hi,
You might want to look at the PIMORONI site [1], single and dual NVMe
adapters up to 2280 in length. You can boot from the single slot
adapters but not the dual as the existing bootstrap code doesn't
recognise the packet switcher/multiplexer although I understand this
is being worked on.
The PiHut [2] resell some of the PIMORONI adaptors as well as Argon
cases with adapters for NVMe with Pi5 and Pi4. The latter via a USB
bridge which is ugly.
[1] https://shop.pimoroni.com/search?q=NVMe
[2] https://thepihut.com/
--
Bob Dunlop
--
Next meeting: Online, Jitsi, Tuesday, 2024-06-04 20:00
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Re: [Dorset] Running OpenSSH server? Check for a fix.
Hi, patches for Gentoo are available: # emerge --sync # emerge --update openssh # /etc/init.d/sshd restart On Mon, Jul 01 at 12:46, Ralph Corderoy wrote: ... > Those running OpenSSH's SSH server, you'll know if you are, might want > to see if their distribution is offering an upgrade and if so, > accept it. There's news of a flaw and distros are making a fix > available. https://www.qualys.com/regresshion-cve-2024-6387/ -- Bob Dunlop -- Next meeting: Online, Jitsi, Tuesday, 2024-07-02 20:00 Check to whom you are replying Meetings, mailing list, IRC, ... http://dorset.lug.org.uk New thread, don't hijack: mailto:dorset@mailman.lug.org.uk
Re: [Dorset] Scripting assistance please
Hi, On Mon, Aug 17 at 09:00, Peter Merchant wrote: ... > The book on unix with a chapter on scripting that I pulled off the shelf > is dated 2000, so not much use. Why not ? Unless the book is incredably badly written or non-portable linux scripting does not change that much, at least with tools like sh/bash. I'd expect Unix shell scripts I wrote 30 years ago at university to work on a modern linux box without major difficulty. It's not some fly by night constantly changing system after all. As for the problem you're posed. Since the interface you want to play with is web based the first thing I'd suggest is that you study the manpage for the wget command. Very useful for this sort of stuff. -- Bob Dunlop -- Next meeting: Dorchester, Tuesday 2009-09-01 20:00 Dorset LUG: http://dorset.lug.org.uk/ Chat: http://www.mibbit.com/?server=irc.blitzed.org&channel=%23dorset List info: https://mailman.lug.org.uk/mailman/listinfo/dorset
Re: [Dorset] Maemo and the Nokia N900
Hi, On Mon, Oct 12 at 04:19, Andrew Drapper wrote: > What do people on LUG think of Maemo and the Nokia N900 that will use it as > it OS. How well will it stand up to the iPhone or Google Androude phones? There's been some discussion on the HantsLUG list. Maemo 1-4 have been quite well received and Hugo likes his N800. I think it's safe to say that several of us are looking into what sort of deal we can get from the various mobile operators. Buying one outright the cheapest I've seen is #450, or you can get one "free" if you sign a #35pm two year contact. This is a strange usage of the word free that I don't understand. I guess most are looking for something between the two extremes. Best guess on UK availability seems to be end of the month. One concern I've seen raised a few places is what happens to support when the N910 and Maemo6 comes out. People are complaining that Maemo5 is not available on the older platforms. I think this is a little unfair as they don't have the necessary hardware support for some of the features, and I guess you would be free to backport any application you really wanted. iPhone and Android, I know nothing. -- Bob Dunlop -- Next meeting: Dorchester, Tuesday 2009-11-03 20:00 Dorset LUG: http://dorset.lug.org.uk/ Chat: http://www.mibbit.com/?server=irc.blitzed.org&channel=%23dorset List info: https://mailman.lug.org.uk/mailman/listinfo/dorset
Re: [Dorset] Nokia Discount codes for N900 - run out tomorrow!
On Tue, Oct 20 at 10:50, Ralph Corderoy wrote: > > Hi, Just in case this is of interest to some list members. I know > there's been talk about the phone on #dorset IRC channel. Ralph. None of the codes work for me this morning (Wed 21st), I guess "tomorrow" was a few days back :( Best price SIM free that I've seen is MobilePhonesDirect who have them at #450 inc VAT. -- Bob Dunlop -- Next meeting: Dorchester, Tuesday 2009-11-03 20:00 Dorset LUG: http://dorset.lug.org.uk/ Chat: http://www.mibbit.com/?server=irc.blitzed.org&channel=%23dorset List info: https://mailman.lug.org.uk/mailman/listinfo/dorset
Re: [Dorset] Real-time Linux
Hi, On Tue, Apr 20 at 05:48, Terry Coles wrote: > Can anyone answer a few queries about coding for a real-time Linux kernel? Perhaps you should define "real-time" for a start. Are you looking to achieve timing constraints in the tens of millisecond range, microseconds or nanoseconds ? Are you looking at a genuine real-time linux kernel (which are real hairy beasts) or a recent 2.6.x system with the "real-time" scheduler capability. I've seen people talk about real-time before, and then on analysis the real requirements have had demands in the 10s or even 100s of milliseconds that could be handled by a conventional system. > 1. I'm assuming that any drivers for the test resources would have to run in > kernel space rather than user space. Is that true? You can write user space drivers in linux (many X-windows graphics drivers could be considered user space drivers) but it's not the norm, and several barriers have to be overcome. One of the primary questions whould be what's the timing requirements ? > 2. How hard would it be for a Windows developer with C and C++ experience to > gain enough knowledge to integrate a driver into a real-time system? Well I've never written a Windows program, and would consider it a pretty daunting task. I couldn't even find the C compiler the one time I looked. The toolset and mindsets are different. Can they write real C in a text file, or are they GUI box joiners ? My first genuine device driver probably took me about 2 weeks from scratch with only the most basic of guides. I was a reasonably competent Unix applications programmer at the time so already knew the basic tools. That was nearly 30 years ago. These days the documentation and guides are a lot better but the whole kernel tends to be more complex. Are you looking to bitbash a few bits in an I/O port or launch a scatter/ gather multi-channel DMA engine ? > 3. Is there anything that we should be aware of, other than the things I've > mentioned above? Depending on how you intergrate your drivers with the kernel you might want to consider liciencing issues. Do you want to release the drivers under GPL ? > 4. Is there a better way? We don't exclude contractors, but the amount of I shan't give you my thoughts about contractors. Don't dispair. We handle lots of near real-time (10-50ms) data on an ARM processor (so not a GHz PC) on a conventional kernel without problem. The same system has one real time critical application that uses the kernel "real-time" schedular capability, we expect that user space app to achieve sub microsecond timing and it does. Can you give us any info on the devices you are trying to control ? -- Bob Dunlop -- Next meeting: Unknown http://dorset.lug.org.uk/ http://www.linkedin.com/groups?gid=2645413 Chat: http://www.mibbit.com/?server=irc.blitzed.org&channel=%23dorset List info: https://mailman.lug.org.uk/mailman/listinfo/dorset
Re: [Dorset] Terminal program
On Wed, Apr 28 at 08:38, Peter Merchant wrote: > Hi, I am going to be 'playing' with some Cisco routers over the next few > weeks, and it is some years since I tried to use a terminal package from > a *nix environment. A forum comment from Ubuntu 7.1 suggests minicom or > gtkterm. Please no! NOT minicom! It's possibly the worst VT100 emulator I have even encountered and has the crankiest confiuration system. Why can only root change and save parameters, why can't you set parameters on the command line ? Open your standard terminal window (Kterm ?), then use picocom to connect to the device: $ picocom -b /dev/ttyS0 That's all there is to it. Simple. Picocom like the venerable old cu does no terminal emulation of its own. It just passes the data straight through to whatever terminal emulator you're already running. Far, far less to go wrong. For gentoo users it's "emerge net-dialup/minicom" but since the source is from http://alioth.debian.org/projects/minicom I guess there's a debian package for it. -- Bob Dunlop -- Next meeting: Unknown http://dorset.lug.org.uk/ http://www.linkedin.com/groups?gid=2645413 Chat: http://www.mibbit.com/?server=irc.blitzed.org&channel=%23dorset List info: https://mailman.lug.org.uk/mailman/listinfo/dorset
Re: [Dorset] Disk size in Asus EEE
On Tue, Jun 22 at 09:15, d-...@hadrian-way.co.uk wrote: > I'm getting a bit confused with the diskspace available on my mother's Asus > EEE > 700. By default, these came with a 4G flash drive and I've added a 4G SD card. > > Xandros seems to have appended the SD Card to the original 4G, because the > Disk > Utility (a GUI tool in the Settings tab) says that all the space is on one > drive. However, it also says that there is only 4G > > In a shell I get: > > /home/user> df -h > Filesystem Size Used Avail Use% Mounted on > rootfs 1.4G 841M 508M 63% / > /dev/sda1 1.4G 841M 508M 63% / > unionfs1.4G 841M 508M 63% / > tmpfs 249M 20K249M1% /dev/shm > tmpfs 128M 24K128M1% /tmp > /dev/sdb1 3.8G 561M 3.2G 15% /media/D: > > Can anyone explain where her other space has gone??? She keeps filling up the > disk, even though there is loads left. I've not used a 700 but I'm guessing disk space is about right. The initial 4G (sda) will also have big chunks reserved for swap and the Xandros recovery partition. Hence only 1.4G for the user. Having had to cleanup a 901 recently I suspect the problme you are hitting is not raw space but inode allocation. Try a "df -i" to check. Xandros seems to leave a lot of temporary files lying around eating up inodes. One cleanup suggested on the web is: sudo find / -iname '.wh*' -delete Also: sudo apt-get clean I tried both of these by remote control. I wonder if talking a seismologist through things step by step is any easier than your mother :-) It gave us some short term relief. Ultimate solution is to replace the aging and poorly supported Xandros with something newer. On the 901 for general use I can recommend Ubuntu Remix 10.4. I don't know if it will fit on a 700. -- Bob Dunlop -- Next meeting: Blandford Forum, Tuesday 2010-07-06 20:00 http://dorset.lug.org.uk/ http://www.linkedin.com/groups?gid=2645413 Chat: http://www.mibbit.com/?server=irc.blitzed.org&channel=%23dorset List info: https://mailman.lug.org.uk/mailman/listinfo/dorset
Re: [Dorset] Clive's Problem with /tmp/.X11-unix.
On Mon, Sep 06 at 01:53, jr wrote:
> hi Ralph,
>
> > ? ?$ ? ? awk -F: '$1 == "root" || $3 ~ /^0*$/ {print NR, $0}' /etc/group
> > ? ?1 root:x:0:
>
> just wondering why the last field's empty (and doesn't contain user 'root')?
>
> man (5) group specifies: group_name:passwd:GID:user_list
It's a common ommission/non-requirement.
All users (root included) get their primary group ID from /etc/passwd,
it's the numeric value 4th field. /etc/group is really about providing
a number/name translation for group IDs and setting the user's supplementary
group IDs.
The fact that a user's primary GID may or may not be in the supplementary
group list is just one of those little pains you have to program around.
If you enjoyed man (5) group you may also like to try man (7) credentials.
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Re: [Dorset] Which distro would you install?
Hi, On Thu, Sep 23 at 06:30, Natalie Hooper wrote: ... > With the above in mind, which distro would you advise me to install on my > new desktop? I was thinking of perhaps openSuse or Fedora but not too sure > if there is one distro considered better for programmers? With all the above in mind I'd suggest Ubuntu as being easy. Not really what I'd call a programmers system but good enough for PC only GUI programming. For hardcore embedded systems programming there's really no choice, Gentoo all the way. No other system lets you set up an entire cross development tool chain and library for a custom target with a single command. I've currently got six cross development environments installed on my work machine and a further three at home. Deleting them is likewise a single command so I only keep the current working set. Gentoo is okay for all the other features but will involve a lot of setup if you want an intergrated multi-media experience. Installation takes a while most of it waiting for things to compile, actual interaction required for a minimal install is under 30 minutes. As for maintaining the system I probably average about 10 minutes a week. So for hardcore programming and PCB design I use Gentoo, but if I'm lazy or for doing anything else I have a netbook with Ubuntu on it. -- Bob Dunlop -- Next meeting: Bournemouth? TBD, Wednesday 2010-10-06 20:00 Meets, Mailing list, IRC, LinkedIn, ... http://dorset.lug.org.uk/ How to Report Bugs Effectively: http://bit.ly/4sACa
Re: [Dorset] Cross development [was Re: Which distro would you install?]
Hi, On Fri, Sep 24 at 09:22, Tim Allen wrote: ... > That's interesting. I'm now at the end of week two setting up a > gcc/Newlib toolchain for m68k (on Debian). Most of the pain has been in > figuring out how to avoid Newlib's I/O and reentrancy overhead, for very > memory-constrained targets, but the initial build sequence wasn't > straightforward either. How would I do this with Gentoo? Well in theory it's simply: crossdev --stable --target m68k-elf--newlib or similar. Unfortunatly I've just tried it and it barfs while trying to build newlib. I've not used m68k in 10 years and have never used newlib, can you give me a valid Gcc target tuple to use and I'll try it again. -- Bob Dunlop -- Next meeting: Bournemouth? TBD, Wednesday 2010-10-06 20:00 Meets, Mailing list, IRC, LinkedIn, ... http://dorset.lug.org.uk/ How to Report Bugs Effectively: http://bit.ly/4sACa
Re: [Dorset] (no subject)
On Fri, Sep 24 at 03:55, Dan Dart wrote: > > http://bit.ly/cvIBAp > > Looks dodgy - since it was sent to everyone - I'd like a little explanation. Spam using URL shortners to try and disguise it's nature. Unless the final destination URLs are of any interest to anyone. SPAM://alternativehealthpharmacy.ru/?cid=44_3 SPAM://buy-digitalshop.ru I'd suggest the mail list drops all meesages from msn.com as the simplest solution. -- Bob Dunlop -- Next meeting: Bournemouth? TBD, Wednesday 2010-10-06 20:00 Meets, Mailing list, IRC, LinkedIn, ... http://dorset.lug.org.uk/ How to Report Bugs Effectively: http://bit.ly/4sACa
Re: [Dorset] [Hampshire] Basic Linux Training
On Fri, Mar 18 at 07:56, Sean Gibbins wrote: ... > It appears that the Open University are now offering a module that > explores the basics of Linux system administration, and that can provide ... OU> This course includes online computer activities - you can access these OU> using a web browser that can play Flash and Shockwave. ^ By the time you've got Shockwave running on your linux box you probably don't need the rest of the course. -- Bob Dunlop -- Next meeting: Bournemouth, Tuesday 2011-04-05 20:00 Meets, Mailing list, IRC, LinkedIn, ... http://dorset.lug.org.uk/ How to Report Bugs Effectively: http://goo.gl/4Xue
Re: [Dorset] Terminal that can do ANSII
On Wed, Oct 12 at 05:48, Terry Coles wrote: > > I'm sure he would have tried that. I may have been guitly of oversimplfying > the question; I think he might be trying to talk to another device over a > serial link, just as you would have done with a VT 100. Can you use gnome- > terminal or xterm to do that? Run picocom in your xterm of choice for this. Picocom handles the serial comms and the xterm interprets the ANSI escape sequences. There is even an easy mechanism to envoke the file transfer program of your choise. Several small programs working well together, true Unix. Just spent the day configuring expect in front of such a combination, so we can now, connect to a unit, work out what baudrate it's running, at, upload three separate software files, check the hardware type and perform a different configuartion sequence for each. Automating 20 minutes of previously tedious production work. Avoid minicom, it tries to do it all, and hence does none of it well. -- Bob Dunlop -- Next meeting: Bournemouth, Tuesday 2011-11-01 20:00 Meets, Mailing list, IRC, LinkedIn, ... http://dorset.lug.org.uk/ How to Report Bugs Effectively: http://goo.gl/4Xue
Re: [Dorset] Ubuntu 11.04
> When did this Unity UI come in (sorry - Debian innocent speaking here)? > My father installed 11.10 a week or two back - gave me a two minute demo ... Well I use Ubuntu on my toy machine, an EEE 901. Unity on 11.04 annoyed me enough that I've switched to xubuntu with 11.10. This now has a annoying kernel panic associated with Wifi operation that makes the machine far from reliable. Apparently this is a known bug with the upstream kernel but I don't really care about that, I'd like to know when there's a known fix. Cannonical seem to have lost their way recently and quality is slipping. I wouldn't use Ubuntu on anything I considered critical. -- Bob Dunlop -- Next meeting: Bournemouth, Tuesday 2011-12-06 20:00 Meets, Mailing list, IRC, LinkedIn, ... http://dorset.lug.org.uk/ New thread on mailing list: mailto:dorset@mailman.lug.org.uk How to Report Bugs Effectively: http://goo.gl/4Xue
Re: [Dorset] Off-topic - Hardware needed
On Tue, Jan 17 at 09:05, Peter Merchant wrote: > I was given a Stamp Processor for Christmas, and in order to play with > it, I want to be able to add bits without soldering them on to the pcb. > The pcb has a header strip by each of the I/O ports. Can anyone tell me > where I can get jacks and/or jumper cables that will attach to these > header pins? I can't find them at RS or Maplins. HobbyTronics[1] have a wide range of components including solderless breadboards and different types of patch leads unfortunatly most are male to male. I guess you're looking for leads with a female connector to fit onto the Stamp boards male pins. They do sell crimp housing and crimps so you could make up you own leads or if you are lucky with pin spacing turn the whole Stamp board upside down and plug it into a breadboard to give you female connections. Myself I'd just reach for the soldering iron. Cheap and reusable. ps. No connection with HT other than I've been a happy customer in the past. [1] http://www.hobbytronics.co.uk/prototyping -- Bob Dunlop -- Next meeting: Bournemouth, second Tuesday 2012-02-07 20:00 Meets, Mailing list, IRC, LinkedIn, ... http://dorset.lug.org.uk/ New thread on mailing list: mailto:dorset@mailman.lug.org.uk How to Report Bugs Effectively: http://goo.gl/4Xue
Re: [Dorset] Android boot-up time
Hi, On Fri, Feb 10 at 01:08, Tim Allen wrote: > Slightly OT question. Someone I know wants to use an SBC running Android > as a UI (using flash disk). The only connectivity required is a UART > serial interface and it will essentially just act as a graphical touch > screen terminal. They have a commercial system and it's taking half a > minute to boot. Does anyone know if it's viable to strip down such a > system so it will boot in a couple of seconds? I don't know about Android I think it starts a few heavy processes and a lot will depend on the SBC. Something with a PC BIOS would just eat you time budget, but in general it can be done. Nice demo at [1]. Also concider suspend or hibernate modes rather than performing a fresh boot on startup. That's what many devices like phones and pads do these days. [1] http://www.embedded-bits.co.uk/2010/1-second-linux-boot-time/ -- Bob Dunlop -- Next meeting: Bournemouth, Tuesday 2012-03-06 20:00 Meets, Mailing list, IRC, LinkedIn, ... http://dorset.lug.org.uk/ New thread on mailing list: mailto:dorset@mailman.lug.org.uk How to Report Bugs Effectively: http://goo.gl/4Xue
Re: [Dorset] Raspberry Pi --- necessary accessories
On Fri, Mar 09 at 01:12, Peter Merchant wrote: > It looks to me that this is the best buy for a keyboard for it, when you > consider that you also might want to add USB wireless networking, USB > disc storage etc. Beware wireless even at 2.4GHz does not equate to WiFi or any other standard. Most keyboards etc are not standards based and need propriatry drivers that are unlikely to be linux friendly. I'd have thought the most useful first peripheral would be a powered USB hub, with it's own mains power brick. Then you can use that to power the Pi and use any old wired keyboard and mouse that you have to hand. HDMI to SVGA is tricky as you are going from digital to analog domains requiring an active convertor. DVI-D or DVI-I (but not DVI-A) would be a lot easier, that's just a simple wiring conversion. -- Bob Dunlop -- Next meeting: Bournemouth, Tuesday 2012-04-03 20:00 Meets, Mailing list, IRC, LinkedIn, ... http://dorset.lug.org.uk/ New thread on mailing list: mailto:dorset@mailman.lug.org.uk How to Report Bugs Effectively: http://goo.gl/4Xue
Re: [Dorset] Raspberry Pi --- necessary accessories
On Fri, Mar 09 at 08:17, Peter Merchant wrote: > On Fri, 2012-03-09 at 14:28 +0000, Bob Dunlop wrote: > > HDMI to SVGA is tricky as you are going from digital to analog domains > > requiring an active convertor. DVI-D or DVI-I (but not DVI-A) would be > > a lot easier, that's just a simple wiring conversion. > > An HDMI to SVGA cable is less than ??4 on ebay, but I'll wait until I get > the rasp-pi to verify the HDMI connector. That almost certainly won't work. Sounds like a rip off merchant. To repeat HDMI is digital, VGA is analog. You will need a digital to analog convertor (DAC) sometimes known as a scaler. I'd expect to pay at least $50. Just found what looks like a useful page on Raspberry Pi peripherals. http://www.raspberrypi-tutorials.co.uk/starting-up-your-raspberry-pi-device/required/ To quote: Note: There is no VGA output available, so older VGA monitors will require an expensive adaptor. -- Bob Dunlop -- Next meeting: Bournemouth, Tuesday 2012-04-03 20:00 Meets, Mailing list, IRC, LinkedIn, ... http://dorset.lug.org.uk/ New thread on mailing list: mailto:dorset@mailman.lug.org.uk How to Report Bugs Effectively: http://goo.gl/4Xue
Re: [Dorset] Options for a 'new' machine
Hi,
> 2. Have any other disenchanted Ubuntu users settled on an alternative
> system that suits them? I have the feeling that there are a lot of
...
My serious (work and home development) systems all run Gentoo with fluxbox
but that's realy for experienced developers only.
The netbook used for browsing and playing with things used to run Ubuntu
until they broke it with Unity. Now it runs Xubuntu which uses Xfce as
it's interface. All the main Ubuntu apps but with a user interface more
atune with us luddites.
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Bob Dunlop
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Re: [Dorset] Connecting a phone to the computer
On Wed, Apr 04 at 10:55, Victor Churchill wrote: ... > I thought I'd be able to see it at /dev/sdf but no: having made a > directory /media/phone I tried to mount it and failed- > victor@ss07 /media 10:43:54 [1290] > $ sudo mount /dev/sdf phone/ > mount: /dev/sdf: unknown device > > How do I find what 'type' of file system it is in order to mount it? I have the following four lines appended to my /etc/fstab which helps a lot with these sorts of devices. /dev/sde/mnt/usbautonoauto,user 0 0 /dev/sde1 /mnt/usbautonoauto,user 0 0 /dev/sdf/mnt/usbautonoauto,user 0 0 /dev/sdf1 /mnt/usbautonoauto,user 0 0 In the meantime it's safe to guess that it's a FAT filesystem. Try: sudo mount -t vfat /dev/sdf /media/phone -- Bob Dunlop -- Next meeting: Bournemouth, Tuesday 2012-04-03 20:00 Meets, Mailing list, IRC, LinkedIn, ... http://dorset.lug.org.uk/ New thread on mailing list: mailto:dorset@mailman.lug.org.uk How to Report Bugs Effectively: http://goo.gl/4Xue
Re: [Dorset] Search engine frustrations
On Wed, May 09 at 11:23, Victor Churchill wrote: > I have tried asking Google (and DuckDuckGo) for [ svn '.revision' ] and [ > svn ".revision" ] and in each case it blithely ignores my punctuation and > of course gives me reams of stuff that while valid is not actually what I > want right now. This may help. Left hand column select "More search tools". Then select "Verbatim". While it's not documented, as well as turning off spell checking, stem extension etc, it seems to allow searching for some punctuation. At least "svc .revison" seemed to work for me after that. -- Bob Dunlop -- Next meeting: Bournemouth, Tuesday 2012-06-12 20:00 Meets, Mailing list, IRC, LinkedIn, ... http://dorset.lug.org.uk/ New thread on mailing list: mailto:dorset@mailman.lug.org.uk How to Report Bugs Effectively: http://goo.gl/4Xue
Re: [Dorset] Search engine frustrations
On Wed, May 09 at 03:22, Victor Churchill wrote: > > Ah. So Google knows what I really want better than I do... ^_^ > I once typed a search into Google and it came back with just one result. Exactly the page I was looking for. The next line was "Having trouble refining your search? Click here for help." That was before the automatic "Buy nuclear reactors on Ebay" links were added. Happy days. -- Bob Dunlop -- Next meeting: Bournemouth, Tuesday 2012-06-12 20:00 Meets, Mailing list, IRC, LinkedIn, ... http://dorset.lug.org.uk/ New thread on mailing list: mailto:dorset@mailman.lug.org.uk How to Report Bugs Effectively: http://goo.gl/4Xue
Re: [Dorset] Where the log entry
On Sun, Sep 09 at 07:49, Ralph Corderoy wrote: > Another thing to help debug this would be to have > > id >>/tmp/timdebug.$$ Another clasic to add is "env >> /tmp/timdebug.$$" and even "set". The startup environment is very different from userspace. What happens in your script or anything it calls if $HOME isn't set ? To name just one common gotcha. -- Bob Dunlop -- Next meeting: 2012-10-?? 20:00 Meets, Mailing list, IRC, LinkedIn, ... http://dorset.lug.org.uk/ New thread on mailing list: mailto:dorset@mailman.lug.org.uk How to Report Bugs Effectively: http://goo.gl/4Xue
Re: [Dorset] Where the log entry
Hi, On Sun, Sep 09 at 09:17, Tim wrote: > Not sure what it telling me. Well it tells me you're running a Debian derivative. > Just for the record, the command to start VNC is the what I type on the > cli and it works perfectly Yes but the system startup environment is very different from the one a user sees at the CLI. One thing to try is capture the error output from your vnc command. your vnc command > /tmp/vnc-err.$$ 2>&1 The 2>&1 is important, it's what makes sure stderr is copied to the file. It occurs to me that perhaps the command is getting called too early in the startup sequence before networking has come up. What init control info have you provided in the file ? Here's the info I provided for an app that needed to be run after networking and syslog were available. You should be able to adapt it. After adding the info to the file I think you'll need to run a command to copy it into the init systems directories, probably "update-rc.d vnc defaults" or similar but I'm not sure of the exact formula. I'm a Gentoo user and Gentoo and Debian differ a lot in this area. ### BEGIN INIT INFO # Provides: vsp-tcp-bridge # Required-Start: $network $syslog # Required-Stop:$network $syslog # Default-Start:2 3 4 5 # Default-Stop: # Short-Description:VSP UDP-TCP bridge daemon ### END INIT INFO -- Bob Dunlop -- Next meeting: 2012-10-?? 20:00 Meets, Mailing list, IRC, LinkedIn, ... http://dorset.lug.org.uk/ New thread on mailing list: mailto:dorset@mailman.lug.org.uk How to Report Bugs Effectively: http://goo.gl/4Xue
Re: [Dorset] Best starter programming language
On Thu, Sep 20 at 10:20, John Horne wrote: > As a side issue, it was also interesting to see that every 2012 Computer > Science fresher at Cambridge Uni will receive a free Raspberry Pi. (In > my day all I got were free punch cards/coding sheets for programming!) What's really depressing is the implication that every student has an HDMI equipped TV to use it with. In my day we had one TV per college. Made you very discriminating about what you watched. Punch card card was very good for making roaches if I remember correctly. -- Bob Dunlop -- Next meeting: 2012-10-?? 20:00 Meets, Mailing list, IRC, LinkedIn, ... http://dorset.lug.org.uk/ New thread on mailing list: mailto:dorset@mailman.lug.org.uk How to Report Bugs Effectively: http://goo.gl/4Xue
Re: [Dorset] Ubuntu spyware?
Hi, On Mon, Dec 10 at 03:34, John Palmer wrote: > At http://www.fsf.org/blogs/rms/ubuntu-spyware-what-to-do > Richard Stallman says: > " > When the user searches her own local files for a string using the Ubuntu > desktop, Ubuntu sends that string to one of Canonical's servers. > " > His article is a bit short on particulars. To what edition(s) of U. is > he referring and to what programs? Does it affect grep or find, for > instance? Ubuntu 12.10 onwards. I believe it's only the GUI interfaces, specificaly Shopping and Music "Lenses" but all of Dash must be suspect. Can't verify as I havn't installed 12.10 since this was first discussed in the Beta. -- Bob Dunlop -- Next meeting: Bournemouth, Tuesday, 2013-01-08 20:00 Meets, Mailing list, IRC, LinkedIn, ... http://dorset.lug.org.uk/ New thread on mailing list: mailto:dorset@mailman.lug.org.uk How to Report Bugs Effectively: http://goo.gl/4Xue
Re: [Dorset] Partition folder capacity
Hi,
> Is there a maximum number of folders you can have in a partition? Is
> this the problem?
I don't know about ext4 specifically but most file systems have a
preset maximum number of files/directories that you can create.
Each file/directory requires one i-node.
The numbers are normally set high enough that you're likely to run
out of space first.
You can find the values set for your file systems with the command
df -i
$ df -i
Filesystem Inodes IUsedIFree IUse% Mounted on
rootfs 3203072 672377 2530695 21% /
/dev/md126 3203072 672377 2530695 21% /
devtmpfs 2216671516 2201511% /dev
tmpfs2217591044 2207151% /run
shm 221759 1 2217581% /dev/shm
/dev/md125 27189248 2046982 251422668% /home
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Re: [Dorset] Can I use hostnames with ssh without editing /etc/hosts
Hi,
On Sat, Aug 17 at 08:44, Peter Merchant wrote:
...
> Whoa!!! You don't configure static IP addresses at the router. They are
> done on the individual hosts/devices.
A static IP address can be configured by the router using DHCP in fact I
find this a very useful feature of DHCP. All my portable devices are
configured as DHCP clients to get dynamic addresses from any network
they are on. When on the home network, the home router supplies them
with static addresses via DHCP so I can easily access them.
All the machines at work (and we have hundreds) have static addresses
assigned via DHCP from a central router. If we need to reconfigure the
network we'd only need to hit the one server rather than manually
reconfigure each individual machine. Dynamic addresses are only issued
in a narrow range for guest devices and this is used as a big security
hint to various firewalls and servers.
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Re: [Dorset] Web pages hanging up
Hi, On Tue, Oct 15 at 01:38, Peter Merchant wrote: > Just to resolve this problem: I changed the wireless settings on the new > d-link router from b/g/n to just b/g and now it all works OK. The > 3com had been set to 'b' only. I don't know what models TalkTalk are shipping but are you aware that theres a fairly massive security hole in many on the D-link domestic routers. Covers at least models DIR-100, DI-524, DI-524UP, DI-604S, DI-604UP, DI-604+ and TM-G5240 see [1] and [2]. Firmware fixes promised by the end of the month. [1] http://www.theregister.co.uk/2013/10/13/dlink_routers_have_admin_backdoor/ [2] http://www.theregister.co.uk/2013/10/14/dlink_plans_firmware_update_to_disable_dbackdoor/ [3] http://www.dlink.com/uk/en/support/security [4] http://www.theinquirer.net/inquirer/news/2300615/d-link-put-a-back-door-in-its-wifi-routers -- Bob Dunlop -- Next meeting: Bournemouth, Tuesday, 2013-11-05 20:00 Meets, Mailing list, IRC, LinkedIn, ... http://dorset.lug.org.uk/ New thread on mailing list: mailto:dorset@mailman.lug.org.uk How to Report Bugs Effectively: http://goo.gl/4Xue
Re: [Dorset] [OT] BT Line Quality
Hi,
On Thu, Jan 23 at 08:21, Ken Adams wrote:
...
> Long time ago in the days of Fidonet, I had to ask BT to change a
> particular setting on my line to improve connections on the modem.
I remember once remarking to a BT engineer that we were getting better
performance than we expected out of a new leased line. He promptly
went out to the green box in the street and "fixed" that. Never heard
of them going the other way.
Biggest improvement in performance would be to get BT off the line.
When my ISP (AA) moved me from BT-wholesale to TalkTalk-wholesale we
nearly trippled our download speed. From sub 4Mb and falling to over
10Mb. Same piece of copper, to the same exchange.
--
Bob Dunlop
--
Next meeting: Bournemouth, Tuesday, 2014-02-04 20:00
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Re: [Dorset] Remote Desktop to a Raspberry Pi
Hi, On Sat, Apr 18 at 07:35, Martin Hepworth wrote: > So whats wrong with ssh on its own, or if need a gui x11 tunnelled over ssh > to an x-server on the remote? Can I also just say Duh? What's wrong with using X11 or as often known X-windows. It's a client/ server system designed from day one to allow remote machines to display graphics on another remote server. It's the default on most Unix/Linux boxes, all be it with remote and local systems being the same machine on todays PCs. At work I just ssh to a remote box, local net or other side of the world. Behind the scenes ssh tells the remote where the graphics display is located. Then any graphics utility I fire off appears in my local machine's desktop, fully intergrated, no problem. Been doing that since 1986 at least. Remote desktop and the like are just tools to help Microsoft Windows to catch up with Unix common practice. If you have firewalls or similar in the way just add -X to your ssh parameters to create an automatic tunnel. ps. Yes I have run X11 over 64kbps ISDN links. It was not zippy but it did work. -- Bob Dunlop -- Next meeting: Bournemouth, Tuesday, 2015-05-05 20:00 Meets, Mailing list, IRC, LinkedIn, ... http://dorset.lug.org.uk/ New thread: mailto:dorset@mailman.lug.org.uk / CHECK IF YOU'RE REPLYING Reporting bugs well: http://goo.gl/4Xue / TO THE LIST OR THE AUTHOR
Re: [Dorset] Vivaldi
Hi, I've looked at Vivaldi for the first time today. Firstly it's closed source. Now I don't look through the source of every program I run, but it's good to know that others can, and help to keep the provider honest. Secondly, has anyone looked at the privacy policies (note plural) yet ? One of the main ones seems to be that for search engines [1]. [[We collect]] ... 3. Social Networks. Your interactions on social networks through the Software & Services; [[We share]] * We may share your information with certain third parties (including, without limitation, search engines, content providers, and advertising networks and platforms) [[Do not track]] ...the Company does not currently respond or recognize DNT Feature signals. Usage implies express consent to transfer data outside EU protection. Now these are small snippets, out of context, and it may be a boiler plate to cover the company against any eventuality, or it may be someone who plans to fund themselves selling your profile to all and sundry. Has anyone who really knows looked at this and voiced an opinion ? [1] http://info.vivaldi.rocks/privacy-policy/ -- Bob Dunlop -- Next meeting: Bournemouth, Tuesday, 2016-05-03 20:00 Meets, Mailing list, IRC, LinkedIn, ... http://dorset.lug.org.uk/ New thread: mailto:dorset@mailman.lug.org.uk / CHECK IF YOU'RE REPLYING Reporting bugs well: http://goo.gl/4Xue / TO THE LIST OR THE AUTHOR
Re: [Dorset] Help on home play project
Hi, On Sat, May 27 at 02:45, Peter Washington wrote: ... > I'd use an "Opto Interrupter", or "Beam Breaker" rather than an > Opto-Coupler, this would apply to both projects. > > In the case of the anemometer, I'd fix an IR Receiver above the spinning > cup shafts and and IR LED below them and count the number of times the beam > is broken, dividing In the by the number of Cup shafts if you want RPM. A useful place to salvage opto switches and LED sources are old ball driven (not the "laser" sensor variety" computer mice. Pickup from the ball is usually via a spindle with an interrupter disk and then a quadrature detector, use one channel for a directionless speed. You'll also find similar on the scroll wheel of modern mice. Extra points for just hacking the anemometer vane direct into the mouse scroll wheel. Then wind speed is just how fast the second scroll input to you PC is spinning. -- Bob Dunlop -- Next meeting: Bournemouth, Tuesday, 2017-06-06 20:00 Meets, Mailing list, IRC, LinkedIn, ... http://dorset.lug.org.uk/ New thread: mailto:dorset@mailman.lug.org.uk / CHECK IF YOU'RE REPLYING Reporting bugs well: http://goo.gl/4Xue / TO THE LIST OR THE AUTHOR
Re: [Dorset] Setting up an NTP Server in a Closed Network
Hi, On Mon, Aug 21 at 04:32, Terry Coles wrote: ... > However, it doesn't work. Everything is sitting at stratum 16 "no trusted clocks", the server won't offer a syncronisation service at this level. The server needs a clock it trusts before it will serve the time. Add the following two lines to your servers config. server 127.127.1.0 fudge 127.127.1.0 stratum 12 This tells the server to use the system clock as a reference at stratum 12. System clock on a Pi is a poor choice since the Pi doesn't have an RTC so will get clobbered on every power cycle but it should get you going. -- Bob Dunlop -- Next meeting: Bournemouth, Tuesday, 2017-09-05 20:00 Meets, Mailing list, IRC, LinkedIn, ... http://dorset.lug.org.uk/ New thread: mailto:dorset@mailman.lug.org.uk / CHECK IF YOU'RE REPLYING Reporting bugs well: http://goo.gl/4Xue / TO THE LIST OR THE AUTHOR
Re: [Dorset] Raspberry Pi Issue with hwclock
Hi, On Sat, Sep 16 at 06:16, Terry Coles wrote: ... > 2. I tried to put the command into an if structure to test to ensure that it > worked, eg > > if [ "rdate -v 192.168.0.2" ]; then > exit 0 > else > exit 1 > fi That's not the way to test the outcome of a command. The [ ] actually delimit the "test" command that performs various tests on it's arguments before exiting with the result. What you've coded there is a test of whether the string "rdate -v 192.168.0.2" is non-zero length. Skip the [] and run the command directly in the if structure. if rdate -v 192.168.0.2 ; then exit 0 else exit 1 fi The return code of the last command is available in the variable $? so you could simplify this to. rdate -v 192.168.0.2 exit $? Or even simpler as this is the last command. exec rdate -v 192.168.0.2 HTH -- Bob Dunlop -- Next meeting: Bournemouth, Tuesday, 2017-10-03 20:00 Meets, Mailing list, IRC, LinkedIn, ... http://dorset.lug.org.uk/ New thread: mailto:dorset@mailman.lug.org.uk / CHECK IF YOU'RE REPLYING Reporting bugs well: http://goo.gl/4Xue / TO THE LIST OR THE AUTHOR
Re: [Dorset] Raspberry Pi Issue with hwclock
Hi, On Sun, Sep 17 at 07:18, Terry Coles wrote: > On Saturday, 16 September 2017 19:09:27 BST Bob Dunlop wrote: > > exec rdate -v 192.168.0.2 > > This only occurred to me last night. When I put the command into my script > without preceding it with 'exec' it appears to work. According to the > references I've found for exec, (including its man page), the command allows > you to wrap the arguments of the target command so that the underlying code > receives them correctly. My rdate command includes one switch and one > argument, so how come it works without the exec prefix? In this case the exec is entirely optional. Force of habit on my part from years of working on tightly constrained machines. Exec is a shell built in command so better often to check the particular shells man page. Anyway the relevant part of the manual is "If command is specified, it replaces the shell.". So when you run a command without the exec prefix the parent shell creates a subshell clone of itself (an expensive operation), then this subshell runs the command by exec'ing it. The exec prefix tells the parent shell not to bother with the subshell creation but to directly exec the target command itself. The exec system call basically replaces the existing process (in this case the shell or subshell) with the new target command (rdate) with the target inheriting all the original processes resources including it's process ID. The cost of that "creating a subshell clone" used to be really horrendous, which was why BSD went to the trouble of creating the vfork() system call in an attempt to reduce this overhead. The vfork man page has some interesting history for people into kernel mechanics. -- Bob Dunlop -- Next meeting: Bournemouth, Tuesday, 2017-10-03 20:00 Meets, Mailing list, IRC, LinkedIn, ... http://dorset.lug.org.uk/ New thread: mailto:dorset@mailman.lug.org.uk / CHECK IF YOU'RE REPLYING Reporting bugs well: http://goo.gl/4Xue / TO THE LIST OR THE AUTHOR
Re: [Dorset] Range of a Cat 5 Ethernet Signal
On Wed, Mar 21 at 11:07, Terry Coles wrote: > Hi, > > We've just re-connected our WMT Webserver with the antenna in its new > location at the far end of the site.?? The server is currently in the old > location so there is about 70 m of armoured Cat 5 cable between the two.?? > The Question is; do we need something a bit more powerful at each end to > drive the lines or do we need something at both ends? By the book 1Gbps, 100Mbps, and 10Mbps should all support 100m. Dodgy termination, cable or connectors will severely reduce the range. Try forcing a drop of the line speed to 10Mbps, often works in dodgy situations. Users who don't check the specs, cables crushed by water pressure, let's try it any way etc. ethtool -s $DEVICE speed 10 duplex full Also "ethtool $DEVICE" will show you the current line settings. $DEVICE is probably eth0 or net0 BTW. -- Bob Dunlop -- Next meeting: Bournemouth, Tuesday, 2018-04-03 20:00 Meets, Mailing list, IRC, LinkedIn, ... http://dorset.lug.org.uk/ New thread: mailto:dorset@mailman.lug.org.uk / CHECK IF YOU'RE REPLYING Reporting bugs well: http://goo.gl/4Xue / TO THE LIST OR THE AUTHOR
Re: [Dorset] Range of a Cat 5 Ethernet Signal
On Wed, Mar 21 at 12:36, Terry Coles wrote: ... > I'm think more about the specifications of the driver/receivers in the two > devices. That spec that you referenced says that the maximum operating > voltage is 125 V, but we're not going to get that from a Raspberry PI! I > haven't managed to find anything on that aspect of the spec, but as I > understand it, each driver/receiver pair is current driven, so the driver > increases the voltage until the current required is achieved. I would expect > cheap switches (especially ones that run off low voltage DC (5 V for the TP- > Link and 12 V for the Belkin) would struggle to get the current after 40 -50 > metres or so. The 125V is the minimum inter core DC insulation provided by the cable. It's there because the cable may be carrying 57V DC PoE power and has nothing to do with the signalling level which is about +-2V differential. Each end is transformer coupled with about 1500V isolation. Again because of spec. It's an important safety as cables may be used for interbuilding connections. I've never seen a sub spec driver that wasn't just plain faulty/broken, well maybe some early D-link switches in the early 1990's. Similarly there isn't an Ethernet+ option despite what some marketing departments think. It's built to spec or it isn't Ethernet. Pi's will be built to the spec although there was a rumour of some made without the isolation transformer in the socket. I'd expect to have seen a safety recall if this had been true. > I was wondering how much people knew about commercial switches and whether > they specify a maximum cable length? Yes the spec says 100m. > Finally, can Ethernet boosters be obtained, or can we only get away with a > repeater half-way down the cable run? By repeater I assume you mean a bridge or switch. I believe the spec says you can only have three but that may have been repealed. You can also get extenders that convert the signals (and often protocols) to non-Ethernet signalling for covering long distances. Good ones cost more that the rest of your kit combined. We normally convert to twin fiber optic for longhaul. -- Bob Dunlop -- Next meeting: Bournemouth, Tuesday, 2018-04-03 20:00 Meets, Mailing list, IRC, LinkedIn, ... http://dorset.lug.org.uk/ New thread: mailto:dorset@mailman.lug.org.uk / CHECK IF YOU'RE REPLYING Reporting bugs well: http://goo.gl/4Xue / TO THE LIST OR THE AUTHOR
