[Hampshire] Post MySQL talk supplement.
Hi everyone, Thanks very much to those who attended, I can go on about MySQL and PostgreSQL for a long long time. I will pop along next month with LibreOffice Base, and a MySQL Workbench demo setup on my laptop for anyone who wants to see it. I have posted some notes here: https://gist.github.com/4706218 For anyone using MySQL now in anger, and needs some help managing it I recommend High Performance MySQL 3rd Edition for MySQL 5.5, http://shop.oreilly.com/product/0636920022343.do For anyone looking for a good resource on Database Design and SQL, it doesn't get much better than The Art of SQL, without burying too deep into the Relation Model, http://www.amazon.co.uk/The-Art-SQL-St%C3%A9phane-Faroult/dp/0596008945/ Rich -- Richard Bensley - 07540878285 -- Please post to: Hampshire@mailman.lug.org.uk Web Interface: https://mailman.lug.org.uk/mailman/listinfo/hampshire LUG URL: http://www.hantslug.org.uk --
Re: [Hampshire] HD activity
Also worth looking at atop which is good for disk activity. Thanks, Anton -- Anton Piatek http://www.strangeparty.com No trees were destroyed in the sending of this message, however, a significant number of electrons were terribly inconvenienced. On 3 Feb 2013 20:34, Benjie Gillam ben...@jemjie.com wrote: iotop is great for diagnosing disk I/O :) On 3 Feb 2013, at 19:28, Rob Malpass li...@getiton.myzen.co.uk wrote: Hi all ** ** For some reason, the external drive that my media centre has all its stuff on has just started working really hard. I’m not sure whether I should be worried but my **ix is very much basic so could someone help me zero in on what might be causing this. ** ** The server currently has no windows open Uptime reveals 0.35, 0.47 and 0.25 Finger reveals only two users logged in (me from ssh on another box and me on console) ** ** Normally at this stage, I’d do a netstat –a and or a ps aux to find out what’s using the CPU and network but having done both, I see a lot of stuff I can’t interpret (for example CPU processes enclosed in square brackets) and besides which, as I’m in gnome on the desktop, I’d assume these are all required processes. ** ** What other checks should I be doing? ** ** …and while on the subject, I need to tie down this machine’s firewall a bit better. Using ufw, I want a rule which allows any sort of access from my subnet (and obviously nothing beyond) – can anyone give me the syntax?* *** ** ** Cheers Rob -- Please post to: Hampshire@mailman.lug.org.uk Web Interface: https://mailman.lug.org.uk/mailman/listinfo/hampshire LUG URL: http://www.hantslug.org.uk -- -- Please post to: Hampshire@mailman.lug.org.uk Web Interface: https://mailman.lug.org.uk/mailman/listinfo/hampshire LUG URL: http://www.hantslug.org.uk -- -- Please post to: Hampshire@mailman.lug.org.uk Web Interface: https://mailman.lug.org.uk/mailman/listinfo/hampshire LUG URL: http://www.hantslug.org.uk --
Re: [Hampshire] Registering on the WordPress website
I never set a mailman password, and think that the effort of sharing passwords is unlikely to be worth the effort. I'm not sure how to simplify WordPress logins, maybe only giving draft and comments access by default? OpenID helps as you can then just use a Google address or similar. Thanks, Anton -- Anton Piatek http://www.strangeparty.com No trees were destroyed in the sending of this message, however, a significant number of electrons were terribly inconvenienced. On 3 Feb 2013 18:00, Chris Dennis cgden...@btinternet.com wrote: Hello HantsLUGgers Here's an idea... Since membership of the LUG is defined as being subscribed to this mailing list, it would make sense to link the list with WordPress's users. In other words, subscribers to this mailing list should be able to log in to the WordPress site in order to add and edit content. Does that make sense? A quick search hasn't revealed any obvious ways of doing it, although there is some discussion at http://mail.python.org/** pipermail/mailman-users/2011-**June/071787.htmlhttp://mail.python.org/pipermail/mailman-users/2011-June/071787.htmlThere is also a 'MailMan Widget' for WordPress that does the reverse: maybe that's the way to go. Perhaps it would need a regular job to extract the current list of subscribers from MailMan and use that to update the WordPress user list. The first problem would be that MailMan just needs an email address, whereas WordPress works in terms of usernames. And the other problem would be to find a way to share passwords between the two systems securely. If anyone thinks that this is a) a good idea, and b) feasible, please let me know. (But I'll be away until Thursday, so don't expect any immediate replies from me.) cheers Chris -- Chris Dennis cgden...@btinternet.com Fordingbridge, Hampshire, UK -- Please post to: Hampshire@mailman.lug.org.uk Web Interface: https://mailman.lug.org.uk/**mailman/listinfo/hampshirehttps://mailman.lug.org.uk/mailman/listinfo/hampshire LUG URL: http://www.hantslug.org.uk --**--**-- -- Please post to: Hampshire@mailman.lug.org.uk Web Interface: https://mailman.lug.org.uk/mailman/listinfo/hampshire LUG URL: http://www.hantslug.org.uk --
[Hampshire] Raspberry Pi Questions
Hi, Having actually seen and photographed a Raspberry Pi I think I'm sold on the idea of them. I currently have an Ethernet switch under the TV, spare power and a CRT (composite TV input) though I do plan to replace it with a flat TV of some sorts eventually (HDMI input). It seems to make sense that a RPi Model B makes sense, it would be small, silent and fun - it appeals to my inner geek. I've a few questions: 1) Where is the best place to get one? Maplin or Farnell or RS? 2) What else does it need? An SD card for the OS and local storage A case A USB power supply A USB keyboard and mouse if you want to drive it directly -- Adam Trickett Overton, HANTS, UK We are all atheists about most of the gods that humanity has ever believed in. Some of us just go one god further. -- Richard Dawkins -- Please post to: Hampshire@mailman.lug.org.uk Web Interface: https://mailman.lug.org.uk/mailman/listinfo/hampshire LUG URL: http://www.hantslug.org.uk --
Re: [Hampshire] Raspberry Pi Questions
On Monday 04 Feb 2013 20:13:45 Dr A. J. Trickett wrote: Hi, Having actually seen and photographed a Raspberry Pi I think I'm sold on the idea of them. I currently have an Ethernet switch under the TV, spare power and a CRT (composite TV input) though I do plan to replace it with a flat TV of some sorts eventually (HDMI input). It seems to make sense that a RPi Model B makes sense, it would be small, silent and fun - it appeals to my inner geek. I've a few questions: 1) Where is the best place to get one? Maplin or Farnell or RS? 2) What else does it need? An SD card for the OS and local storage A case A USB power supply A USB keyboard and mouse if you want to drive it directly I got mine from Farnell. Always found them good. SD card is required (anything above 2GB I think). A case is a good idea, though no idea where to source one. Phone charger (for modern smart phone will work fine). Cheers, Tim B. -- Hampshire Linux User Group Chairman -- Please post to: Hampshire@mailman.lug.org.uk Web Interface: https://mailman.lug.org.uk/mailman/listinfo/hampshire LUG URL: http://www.hantslug.org.uk --
Re: [Hampshire] Raspberry Pi Questions
Hi Adam On 04/02/13 20:13, Dr A. J. Trickett wrote: I currently have an Ethernet switch under the TV, I run mine with a Edimax USB WIFI dongle which OpenElec just worked with It seems to make sense that a RPi Model B makes sense, it would be small, silent and fun - it appeals to my inner geek. I've a few questions: 1) Where is the best place to get one? Maplin or Farnell or RS? I got mine from RS - I couldn't really complain although I would have like more in the way of tracking and communication from them. 2) What else does it need? An SD card for the OS and local storage RS sell a pre-loaded SD card, although I didn't choice, I had a spare 2GB SD which I have loaded OpenElec and Raspbian without issue A case I opt'd for one these and it does the job ok http://uk.rs-online.com/web/p/processor-microcontroller-development-kits/7644385/ Lego seems to be another popular option A USB power supply I powered the pi from the USB port on the TV, not an option on the current TV I'd imagine but something to consider moving forward. However as soon as you start a few USB devices then a powered USB hub seems to be required, I did use mine with a webcam and motion for a bit, I found I could power the pi of the powered USB hub and then loop it back onto the HUB for accessing the webcam. A USB keyboard and mouse if you want to drive it directly I have only used a USB keyboard for installations, after that I have done everything remotely. Hope this helps Rgds Peter. -- Please post to: Hampshire@mailman.lug.org.uk Web Interface: https://mailman.lug.org.uk/mailman/listinfo/hampshire LUG URL: http://www.hantslug.org.uk --
Re: [Hampshire] Raspberry Pi Questions
On 04/02/2013 20:13, Dr A. J. Trickett wrote: 1) Where is the best place to get one? Maplin or Farnell or RS? I've got mine from Farnell (2 off) and RS - Farnell were faster, but the RS one was ordered in the initial rush for them, so took forever - they are quicker now. 2) What else does it need? An SD card for the OS and local storage As others have said, a 2GB+ one. Some cards work well, and others badly. I've had some (Sandisk mostly) which either didn't work at all, or failed after a couple of unexpected reboots. Integral ones seem pretty good (all of mine currently have 2GB Integral ones). If you use one larger that 2GB, you can usually expand the main partition to use up the whole of the card, the first time you boot. That's certainly the case with Raspbian. A case Farnell sell coloured plastic ones for a fiver - I went for clear, so you can still see the insides. The problem with most cases is that they hide the GPIO pins, one of the USPs of this wonderful machine. I've also just bought a Piface (I/O card with buffere I/O pins, 8 LEDs and a couple of relays) which stacks onto the Pi like an Arduino shield, and that wouldn't fit in most cases either. For those occasions, Lego is probably your best bet, or just leave it bare and be careful handling it. A USB power supply Yes, almost any micro-USB phone charger (1 Amp is plenty, 700mA usually enough), though I also run mine from USB ports on laptops, or even better from the back of my router (so the Pi is powered on whenever the router is). A USB keyboard and mouse if you want to drive it directly Yes, but if you pre-edit the config files (i.e. mount the partitions just after you have used dd to write the OS image to the SD card), including forcing SSH server on, you can run it without ever attaching keyboard or screen to it. I've bought one of those tiny wireless keyboard/touchpad things (about the same size as the TV remote control [1]) - you plug the dongle in to a USB port on the Pi and it just works. For a portable solution, the Motorola Atrix LapDock [2] (screen and keyboard) looks a bit like a laptop - it was designed to take a Motorola mobile phone, but with some connector magic (connecting male micro USB and male micro HDMI connectors on the LapDock to their female full-size equivalents on the Pi), it works pretty well. Simon [1] http://www.amazon.co.uk/gp/product/B004FSFYG8 [2] http://www.amazon.co.uk/Motorola-Laptop-Station-Cradle-Lapdock/dp/B00B0VHW90 (though I got mine from Ebay) -- Please post to: Hampshire@mailman.lug.org.uk Web Interface: https://mailman.lug.org.uk/mailman/listinfo/hampshire LUG URL: http://www.hantslug.org.uk --
[Hampshire] Another Raspberry PI question.
Hi, I have found lots of web site detailing how to drive a relay from a Raspberry PI, for example, turning 240V AC mains devices on and off. What I cannot find is how to have the PI detect if 240V is on a wire or not. I.e. If a 240 AC wire is powered or not? It is a useful function for home automation purposes. For example, I could use it in order to make a log of when the heating is switched on, or use existing 240V AC main light switches to provide inputs to the Raspberry PI, and let the PI control something else as a result. Done anyone know of any sort of detect 240V AC adapter for the GPIO of the Raspberry PI? Kind Regards James -- Please post to: Hampshire@mailman.lug.org.uk Web Interface: https://mailman.lug.org.uk/mailman/listinfo/hampshire LUG URL: http://www.hantslug.org.uk --
Re: [Hampshire] Another Raspberry PI question.
You definitely need to isolate between the mains and GPIO. An optical isolator would seem to be the ideal device. http://electronics.stackexchange.com/questions/50782/ac-detection-for-microcontroller I am not an electrical or electronics engineer, I know just enough to be dangerous. On 4 February 2013 21:49, James Courtier-Dutton james.dut...@gmail.comwrote: Hi, I have found lots of web site detailing how to drive a relay from a Raspberry PI, for example, turning 240V AC mains devices on and off. What I cannot find is how to have the PI detect if 240V is on a wire or not. I.e. If a 240 AC wire is powered or not? It is a useful function for home automation purposes. For example, I could use it in order to make a log of when the heating is switched on, or use existing 240V AC main light switches to provide inputs to the Raspberry PI, and let the PI control something else as a result. Done anyone know of any sort of detect 240V AC adapter for the GPIO of the Raspberry PI? Kind Regards James -- Please post to: Hampshire@mailman.lug.org.uk Web Interface: https://mailman.lug.org.uk/mailman/listinfo/hampshire LUG URL: http://www.hantslug.org.uk -- -- Philip Stubbs -- Please post to: Hampshire@mailman.lug.org.uk Web Interface: https://mailman.lug.org.uk/mailman/listinfo/hampshire LUG URL: http://www.hantslug.org.uk --
Re: [Hampshire] Another Raspberry PI question.
On Monday 04 Feb 2013 21:49:18 James Courtier-Dutton wrote: Hi, I have found lots of web site detailing how to drive a relay from a Raspberry PI, for example, turning 240V AC mains devices on and off. What I cannot find is how to have the PI detect if 240V is on a wire or not. I.e. If a 240 AC wire is powered or not? Done anyone know of any sort of detect 240V AC adapter for the GPIO of the Raspberry PI? I don't know of any pre-made boards/kits, so it's probably a DIY job. There are (at least) two ways of doing this. You can either sense voltage, in which case you need some form of rectifier, potential divider and buffer circuit (possibly an optocoupler). There is some info here: http://www.edaboard.com/thread206697.html Alternatively you can sense current, in which case you can use a non-contact current sensor (possibly a current transformer or hall-effect sensor), and some suitable amplification. Some info here: http://talk.jeelabs.net/topic/49 Just be aware that the arduino kit works on 5v DC signal levels, whereas RPI works on 3.3v, so although this has been done for Arduino, it will require a small tweak for RPI. There are also a range of mains voltage and current monitoring ICs available which will interface nicely with the PI over SPI or I2C, however, these require printed circuit boards to be made. Not too difficult, but another thing to learn. Personally, I'd use a current transformer and a suitable interface IC. Cheers, Tim B. -- Hampshire Linux User Group Chairman -- Please post to: Hampshire@mailman.lug.org.uk Web Interface: https://mailman.lug.org.uk/mailman/listinfo/hampshire LUG URL: http://www.hantslug.org.uk --
