March 2012 - main

Any UDP comms experts here?
by Mark Rogers 16 Mar '12

16 Mar '12

I have a device I need to talk to via UDP from within PHP (although it feels like my problem here is a Linux one not a PHP one as everything is being done at the socket level anyway). I am sending a request to an Ethernet module in a PLC, and if I get the addressing wrong in my request then I get an error response back from the PLC as expected (by which I mean a 22 byte message sent via UDP containing the relevant error code) - I see this in my PHP code and in a Windows (Winsock-based) app I have that lets me send test queries and see the responses. However, when I get my addressing correct, whilst the Windows app gives me the response associated with the request I made, in my PHP/Linux code I just get no response (my code hangs up waiting). The PHP code I'm struggling with is: // Create a socket $socket = socket_create(AF_INET, SOCK_DGRAM, SOL_UDP); // Build the message $msg = hex2str('80 00 02 00 01 00 00 11 00 00 05 01'); // Send the message socket_sendto($socket, $msg, strlen($msg), 0, '192.168.251.132', '9600'); // Get the response - this line never returns socket_recvfrom($socket, &$buf, /*Max response length*/250, /*Flags*/0, &$ip, &$port); I would guess that the Ethernet module in the PLC either responds immediately with a response to tell me I have the address wrong, or else has to go off and collect some data before sending it back, although the time this takes is milliseconds. If I set Flags to MSG_DONTWAIT the code no longer hangs; it just returns no characters, even if I put a delay of a couple of seconds before the function call. I'm pretty sure that the key to the solution lies in getting the flags right but there I'm stumped due to lack of knowledge (and everywhere I can find sample code the above works fine). The list of possible flags is in the PHP docs[1] but I think a fuller list would be those listed in "man 2 recv" Any suggestions? [1]http://www.php.net/manual/en/function.socket-recvfrom.php -- Mark Rogers // More Solutions Ltd (Peterborough Office) // 0844 251 1450 Registered in England (0456 0902) 21 Drakes Mews, Milton Keynes, MK8 0ER

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How to get rid of this duff directory?
by Chris Green 15 Mar '12

15 Mar '12

I think this may well be connected with my recent question about automounting. How do I get rid of this broken .gvfs directory:- -rw------- 1 chris chris 0 2012-01-03 10:28 .gtk-bookmarks -rw-rw-r-- 1 chris chris 82 2011-12-29 11:18 .gtkrc-2.0 d????????? ? ? ? ? ? .gvfs drwxr----- 2 chris chris 4096 2012-03-11 17:04 .hplip drwxrwxr-x 3 chris chris 4096 2012-02-15 20:20 .icedtea I can't even ls it directly:- chris$ ls -d .gvfs ls: cannot access .gvfs: Permission denied -- Chris Green

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What do these "Kernel Errors" mean?
by Chris Green 11 Mar '12

11 Mar '12

In my daily logwatch E-Mail I have just noticed the following:- WARNING: Kernel Errors Present EXT2-fs (sdd): error: can't find an e ...: 1 Time(s) EXT3-fs (sdd): error: can't find ext3 ...: 1 Time(s) ... ... ... usb 2-1.1: device descriptor read/64, error -32 ...: 4 Time(s) This possibly explains why the USB flash drive that was /dev/sdd failed to automount. It can be mounted without problems manually using a straightforward mount command. Can anyone explain what I need to do to fix it? The flash drive has a FAT16 file system on it as is normal I think. -- Chris Green

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Gimp help for non-artistic amateur...
by Mark Rogers 09 Mar '12

09 Mar '12

I have a (more-or-less) circular logo. I want to create a new logo which is basically a stack of coins, with the circular logo being the head of the top coin. Sounds simple but it's a bit beyond me - anyone with some actual talent care to point me in the right direction? Mark -- Mark Rogers // More Solutions Ltd (Peterborough Office) // 0844 251 1450 Registered in England (0456 0902) 21 Drakes Mews, Milton Keynes, MK8 0ER

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OT: Reliable ADSL VPN routers with 3G fallback?
by Mark Rogers 09 Mar '12

09 Mar '12

Any recommendations? Draytek 2830 (about £140+VAT) seems to be popular, although you need a 3G USB dongle as well. I'm going to be installing a small Linux box (see, almost on topic really!) at a remote site; it's job will be to collect data and send it to us via ADSL or (if ADSL unavailable) via 3G; VPN access required to allow us to reliably get back into the unit remotely if we need to. Not going to see all that much data traffic and never more than 1 or 2 people connected via VPN (usually nobody), so the Draytek may be overkill. -- Mark Rogers // More Solutions Ltd (Peterborough Office) // 0844 251 1450 Registered in England (0456 0902) 21 Drakes Mews, Milton Keynes, MK8 0ER

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1s cron-a-like
by Mark Rogers 08 Mar '12

08 Mar '12

I need to run a script every second. The script will complete within milliseconds so the hardware is capable, all I am looking for is a reliable way to schedule it. Basically I want a higher-resolution cron. Any suggestions? One option is to write a script which runs every minute and does along the lines of: for($i=0;$i<=59;$i++) { // do something sleep(1) } .. but I'd much rather find a daemon capable of kicking off the script every second (and ideally more flexibly like cron does, and with the logging capability etc that cron has). -- Mark Rogers // More Solutions Ltd (Peterborough Office) // 0844 251 1450 Registered in England (0456 0902) 21 Drakes Mews, Milton Keynes, MK8 0ER

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[ALUG Announce] ALUG Norwich Pub Meet Thursday 8th March
by Viperfang 05 Mar '12

05 Mar '12

ALUG Announce Please send announcements to Announce(a)lists.alug.org.uk Unsub, change settings via http://lists.alug.org.uk/mailman/listinfo/announce ----- Hello Norwich Aluggers, Our monthly ALUG Norwich social meeting will be held this Thursday, 8th March at The Coach and Horses (82 Thorpe Road, Norwich, NR1 1BA). The meeting officially starts at 8pm, although some people may arrive earlier. More information on those people can be found on the list and the IRC channel. If you are unsure if you will recognise us then make yourself and your intent to attend known by either posting on list or visiting us on IRC so we can look out for you rather than hiding in the corner. Optionally you could ask at the bar if they know where the geeky computer weirdos are and they'll point you in the right direction (seriously!). Another possibility is look for heaps of electronics on a table that may possibly look like movie props that would used for detonating explosives. Feel free to bring electronics/laptops/gadgets to the meet, you will by no means be alone. Ben Bewick aka Viperfang NB: This mail is automated, please refer to the usual sources for more information. ALUG Contact Details: Website : http://www.alug.org.uk/ IRC : #alug on irc.alug.org.uk List : http://lists.alug.org.uk/mailman/listinfo Twitter : http://twitter.com/anglianlug Identica: TBA Facebook: http://www.facebook.com/group.php?gid=2381613902 ----- Send discussion replies to main(a)lists.alug.org.uk (Reply-To set) Unsub, change settings via http://lists.alug.org.uk/mailman/listinfo/announce

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Outlook "Rich Text" format (Not OT!!)
by Mark Rogers 02 Mar '12

02 Mar '12

One of my customers (using Outlook via Exchange) keeps sending me winmail.dat attachments. I know from experience that this means somewhere the message is being sent as "Rich Text" rather than "HTML". However he's checked and Outlook is set to use HTML. Any suggestions? I don't have Outlook installed (I don't think they have a Linux version yet :-), although I think it's possibly at an Exchange level anyway, and I know some people her administer both. It seems to be only affecting me - they haven't explicitly said this but I get the impression they can send attachments to (eg) Hotmail and Gmail which (as far as I know) don't support Rich Text either, so it may be something somewhere as got configured against my email address. But I'm just speculating! Something else they haven't said, but I can hear them thinking it, is "why don't you just use Outlook like everyone else", so I'd like to show this is a config problem their end not just me being "non-standard". Grrrrr.... Mark PS: I do have tnef installed so I can extract winmail.dat files but when all they're sending me is screenshots it's a pain not to be able to read them inline in Thunderbird. -- Mark Rogers // More Solutions Ltd (Peterborough Office) // 0844 251 1450 Registered in England (0456 0902) 21 Drakes Mews, Milton Keynes, MK8 0ER

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