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10369 discussions

Sort of philosophical question about Web/Client/Server workings
by Chris Green 17 Jun '12

17 Jun '12

Every time I try and do some web application programming that involves forms (i.e. getting data from a user) it ends up being far more complicated than I expect (and more complicated than it should be I feel). Anywhere else that one programs something to get some data from a user it's fairly direct and simple:- Output something to ask a question Wait for user to enter response Get return with the response OK, it's a bit more complex/messier when using a GUI because there isn't necessarily a simple single thread but it still comes down to the program waiting for an event and, when the event happens, it gets handed some data. However when web programming it's nothing like this, one can't simply ask a question and get the answer. Say one has a PHP script running server side, it creates a form which is then displayed when the client requests it and the client fills in the form. The trouble is that there's no direct way for the PHP script that created the form to get the result - at least there isn't in any of the environment/frameworks that I've used. What happens is that there is *another* script which gets run (server side) when the client submits the form duly filled in. This other script has no direct connection with the script that created the form, no common environment, nothing. It's thus very difficult to write simple form driven applications as one can't simply display a form and get the data from the form in 'one place' as it were. Am I missing something obvious here? -- Chris Green

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xterm input delay and alsamixer display screwed up
by Srdjan Todorovic 16 Jun '12

16 Jun '12

Hi all, If I run KDE on the laptop and run Konsole or xterm, I can type commands immediately. Running alsamixer is also fine. Running fluxbox with xterms, input into xterm is delayed on startup by at least 10 to 30 seconds. Nothing echoed to the terminal while I type. Eventually it will show up. Running alsamixer in it caused bits of the ncurses display to screw up, last time I ran it. The volume control levels would be half-drawn etc. Any suggestions what might be the cause and how to fix? I'll try disabling xorg compositing as suggested here: http://www.linuxquestions.org/questions/slackware-14/xterm-delayed-input-fr… but I'd rather like to keep compositing alive any time I run KDE... Thanks, Srdjan

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How to get rid of "Notice: trying to get property of a non-object" errors in PHP
by Chris Green 15 Jun '12

15 Jun '12

I'm trying out a chunk of downloaded software and it's actually quite close to what I want. However it's outputting *hundreds* of "Trying to get property of non-object" errors which are somewhat distracting as there are more of them than actual data. I'm pretty sure the reason they're appearing is because the code is accessing lots of values before they're created (and presumably doing the right thing when they're null). It's not just in one place in the code so I can't very easily go and change the code at every place this is happening. Is there a way to turn of this particular warning? I'd rather not turn of all warnings and I'd rather do it just for this application rather than everywhere (I want to see warnings on code I've written!). -- Chris Green

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[ALUG Announce] ALUG Norwich Pub Meet Thursday 14th June
by Viperfang 14 Jun '12

14 Jun '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, 14th June 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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Linux Mint 12 Wireless Issues
by Paul Grenyer 13 Jun '12

13 Jun '12

Hi All I've a new Lenovo T520 and I've installed the latest Linux Mint on it, but the wireless is painfully slow. I can't even log into my router's admin page. If I reboot into Windows 7 the speed is fine. I haven't tried a wired connection yet. I'm hoping that the wired connection is fast and might update some drivers as part of the general update process. However, if that doesn't work, I really don't have a clue where to start. The wireless adapter in the T520 is an Intel Centrino Wireless-N 1000. Can you guys give me any pointers, please? -- Thanks Paul Paul Grenyer e: paul.grenyer(a)gmail.com b: paulgrenyer.blogspot.com t: pjgrenyer ACCU Member: License to code. (http://www.accu.org)

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Scientific Linux
by Ted.Harding＠wlandres.net 13 Jun '12

13 Jun '12

Hi All Anyone using Scientific Linux? Not that there's anything specially scientific about it in its generic form. It's basically a clone of Red Hat Enterprise Linux, and it's called "Scientific" because it was put together by FermiLabs and CERN. See: http://en.wikipedia.org/wiki/Scientific_Linux and https://www.scientificlinux.org/ I'd be interested to hear of experiences with it (especially from anyone who has installed scientific extras). Ted. ------------------------------------------------- E-Mail: (Ted Harding) <Ted.Harding(a)wlandres.net> Date: 12-Jun-2012 Time: 23:04:55 This message was sent by XFMail -------------------------------------------------

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How would the team produce a simple web page with a running balance/total on it?
by Chris Green 12 Jun '12

12 Jun '12

I've wanted to do this at several different times and places, some of my solutions are OK'ish but I've not really come up with something neat and tidy for doing it. I want a simple (for the user, and preferably for me too in creating it) web page where a user can enter an amount, probably with a date and a description, that gets added to (or subtracted from) a running total. The user can also see the list of transactions that contributes to the current total. I.e. I want something that looks like a bank statement but can be changed easily on the web page itself. So we'd have something like:- Date Descritption Credit Debit Balance 2012-01-01 Start of year 1234.00 1234.00 2012-02-14 Valentine Pres 12.34 1221.66 2012-03-01 Paid for joke 99.00 1320.66 etc. Plus either a blank line at the bottom of the table to enter new values, or some edit boxes to add new values. There's lots of online spreadsheets out there but since they all tend to be Excel lookalikes they don't do running balances very easily, you have to keep re-entering the balance calculation in the balance column, there doesn't seem to be any easy way to say a column is a calculated value that is always the same calculated value (or at least I've not found it). My implementations so far have either used a database with a very nasty complicated calculated value in the Balance column (that depends on the ordering of the date column which isn't always a good idea if there's more than one entry on the same date) or uses a plugin I have developed for my Wiki which requires the user to edit the wiki page - OK for me usually but not very good for other users. Any bright ideas anyone? Doesn't actually have to be web accessible as it will only have one or two users for each instance so could be done with a dedicated application and a shared file for example. -- Chris Green

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Email clients! - Alpine... anyone use it?
by James Freer 04 Jun '12

04 Jun '12

For a while i've just used the browser for email having found Thunderbird, Evolution and similar so slow on imap. Mutt i managed to set up but being so configurable wasn't to my liking. Alpine seems the fastest of any i've tried... easy to setup - just wondering if anyone else on here uses it. If they do any problems? jmaes

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Multi-VPN configuration
by Mark Rogers 04 Jun '12

04 Jun '12

I always get into a muddle when I try to set up VPN connections but I'm going to have another go.. What I have is lots of Linux "devices" (typically ARM boxes running Debian) which will be plugged into networks giving them Internet access. What I want to achieve is to have them auto-connect to a VPN, such that I am able to access all of them, but also that the end user can connect to their own devices but nobody elses. Ideally I'd also like other VPN capable devices, such as Draytek routers, to be able to join in the party. My starting point - which may well be wrong, is to assume that I want a server running OpenVPN somewhere on t' Internet. (Is that the right place to start?) I find the OpenVPN documentation to be very detailed but hard to narrow it down to any particular usage case unless it's a standard config (eg "road warrier"). What I don't want at my end is to *have* to connect separately to each VPN. Doing so optionally would be good (but would be possible in the same way an extra device could), but it could be I end up with dozens or hundreds of separate segregated VPNs. Furthermore, it's likely that I will want all of the VPNs to have access to certain facilities (eg databases, FTP) on other servers without having to make the other servers join multiple VPNs. -- 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 print stupid Royal Mail price list?
by Chris Green 01 Jun '12

01 Jun '12

The Royal Mail used to provide a neat PDF file which fitted A4 to show their postage prices. The latest version though is a 'booklet' so I can't see any way to actually print it on an A4 printer. This is the link to the PDF:- http://c435158.r58.cf3.rackcdn.com/Royal_Mail_Our_Prices.pdf Can anyone tell me how to split it up into printable pages? I've tried ImageMagick's convert but that didn't default to what I wanted, maybe I need some more options to tell it what to do. -- Chris Green

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Programming question - different approaches to classic command parsing
by Chris Green 29 May '12

29 May '12

Well my Nanode project is progressing (it's the one that has the rather idiosyncratic ethernet handling). The next question is whether to rejig the basic command handling. The Nanode software I'm maintaining/improving is basically very simple, after initialisation it waits for an ethernet UDP packet with a command code and data in it, then it acts on the command and returns (via UDP again) some sort of response. There are currently 34 commands, this will expand somewhat but is unlikely to ever be more than 100 or so. The existing code simply has a switch/case block switching on the command code with the cases handling each command. It's a bit long but is manageable. I'm wondering whether to stay with the existing structure or to go to some sort of table driven approach with an array of something like:- // // // Command table entry structure // struct command { uint32_t cmd; // the command code int (* fnc) (int addr); // the address of the function to call char * str; // the associated LCD string }; (obviously the function parameters may extend/change) A linear search of an array of these won't waste much time, speed isn't of great consequence anyway. Then each command will be a function, tidier and more modular, but will it actually win me anything (or lose anything)? In particular will it use more space, in code or RAM? In code there will be, say, 50 function calls plus a table instead of a switch statement with 50 case: blocks. In RAM there will be lots of smaller functions using a small amount of stack space instead of one big one with lots of local variables. This is using the gcc-avr compiler by the way. My gut feeling is that it probably won't make a big difference either in code space use or in RAM use but it will probably use a little bit more of both. The question then is whether the significant amount of rewriting is worth it for the more elegant (and hence easy to maintain) code. If there's another approach to managing this sort of command driven interface then I'd be interested in hearing about it. -- Chris Green

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Re: [ALUG] Ethernet programming question
by Phil Ashby 28 May '12

28 May '12

Chris Green <cl(a)isbd.net> wrote: > I'm doing some programming of a Nanode board (not far removed from > Arduino) which has an ethernet interface based on the ENC28J60. > ... > However the loop that waits for ethernet packets and deals with them > seems a bit odd to me, in psuedo-code it's something like:- > > while (not reset) > { > get a packet from ethernet > > handle DHCP message > > handle message requesting local display on LCD > > handle ARP request > > handle DNS request > > handle NTP request > > if (still something left) > { > if (ping) > { > respond to ping > } > if (UDP message for us) > { > handle our message > } > } > } > > > What I'm not clear about is whether one packet can only be one of the > above things. Hence, if a DHCP request of some sort has been received > and handled can the *same* packet contain other requests? If not then > why is the code going through all the other calls? Hi Chris - you are correct in assuming that one packet can only be one thing, since a combination of packet type fields (Ethernet frame type, IP frame type, TCP/UDP port number) determine this. > OK, it makes for simpler looking code, no conditionals and/or > switch/case but it somehow seems wrong (and a bit inefficient as each > handle function gets called even if the packet has already been > handled). Just been and looked at the code in github for the Nanode Ethershield and all I can say is yuk! https://github.com/Nanode/EtherShield/blob/master/ip_arp_udp_tcp.c I quote: "The TCP implementation uses some size optimisations which are valid only if all data can be sent in one single packet. This is however not a big limitation for a microcontroller as you will anyhow use small web-pages." Hmmn. I found the code confusing, badly structured and incomplete (eg: it doesn't work if IP options are sent and there is nothing like the full TCP state machine with various timers, backoff controls and such, only a happy path). Of course I may have been looking at different code - got a URL? Phil. PS: http://code.google.com/p/avr-uip/ looks rather better!

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Ethernet programming question
by Chris Green 28 May '12

28 May '12

I'm doing some programming of a Nanode board (not far removed from Arduino) which has an ethernet interface based on the ENC28J60. I'm only modifying the existing software rather than building from scratch but would like to tidy things as much as possible. The ethernet initialisation etc. is standard library code so is cast in stone as it were but I'm puzzling over the higher level ethernet message handling stuff a bit. The system basically handles incoming requests sent over the ethernet interface and replies with instrument data, this part of the code is pretty straightforward. However the loop that waits for ethernet packets and deals with them seems a bit odd to me, in psuedo-code it's something like:- while (not reset) { get a packet from ethernet handle DHCP message handle message requesting local display on LCD handle ARP request handle DNS request handle NTP request if (still something left) { if (ping) { respond to ping } if (UDP message for us) { handle our message } } } What I'm not clear about is whether one packet can only be one of the above things. Hence, if a DHCP request of some sort has been received and handled can the *same* packet contain other requests? If not then why is the code going through all the other calls? OK, it makes for simpler looking code, no conditionals and/or switch/case but it somehow seems wrong (and a bit inefficient as each handle function gets called even if the packet has already been handled). -- Chris Green

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Ripping MP3s
by Chris Walker 23 May '12

23 May '12

I have a Creative Zen MP3 player which I use in my car. I want to tidy up a load of CDs which have accumulated over the years before they go to the bin. They're freebies from newspapers and so aren't worth anything and have the usual half dozen decent tracks followed a dozen rubbish tracks. But I'm stuck trying to rip them to MP3. I've tried k3b but that doesn't offer MP3 as an output option. I've also installed soundkonverter (rather than soundconverter as I'm using kde for a desktop) but despite saying that it can use FFmpeg as a plugin, there is still no MP3 option. Am I doing something wrong? The system is Mandriva 2011 64 bit.

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[very off topic] drill press
by David Reynolds 22 May '12

22 May '12

Hi guys, Does anyone in the Norwich-ish area happen to have (or have access to) a drill press I could use? I am building a guitar from a kit and I need to drill 4 holes with said drill press. Can anyone help? -- David Reynolds david(a)reynoldsfamily.org.uk

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Tonight's Ipswich ALUG meet
by samwise 22 May '12

22 May '12

Well, looks like there's at least three of us out tonight. I thought I'd suggest that after giving it half an hour or so for stragglers, that we might want to try moving back to our old venue The Milestone (now The Mulberry Bush) tonight. It's been reinvented and is a proper real ale pub now, and may well be an improvement on McGinty's ... plus the poker night that turfed us out has long since gone. :) Not sure of the wi-fi situation but it can't be worse than McGinty's! So anyone who wants to come out to play tonight who might be late, come find us at The Mulberry Bush! Peter.

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Can't get 1000Mb/s on ethernet port which should be capable
by Chris Green 19 May '12

19 May '12

I am backing up some data from a Dell Vostro V13 laptop which is currently running xubuntu 10.04 (the reason for the backup is that I'm aiming to install 12.04). The ethernet port is running at only 100Mb/s whereas it's supposed to be a gigabit capable port. Running ethtool shows:- Settings for eth0: Supported ports: [ TP MII ] Supported link modes: 10baseT/Half 10baseT/Full 100baseT/Half 100baseT/Full 1000baseT/Half 1000baseT/Full Supports auto-negotiation: Yes Advertised link modes: 10baseT/Half 10baseT/Full 100baseT/Half 100baseT/Full 1000baseT/Half 1000baseT/Full Advertised pause frame use: No Advertised auto-negotiation: Yes Link partner advertised link modes: 10baseT/Half 10baseT/Full 100baseT/Half 100baseT/Full Link partner advertised pause frame use: No Link partner advertised auto-negotiation: Yes Speed: 100Mb/s Duplex: Full Port: MII PHYAD: 0 Transceiver: internal Auto-negotiation: on Supports Wake-on: pumbg Wake-on: g Current message level: 0x00000033 (51) Link detected: yes Running ethtool on my desktop machine connected to the *same* switch shows:- Settings for eth0: Supported ports: [ TP MII ] Supported link modes: 10baseT/Half 10baseT/Full 100baseT/Half 100baseT/Full 1000baseT/Half 1000baseT/Full Supports auto-negotiation: Yes Advertised link modes: 10baseT/Half 10baseT/Full 100baseT/Half 100baseT/Full 1000baseT/Half 1000baseT/Full Advertised pause frame use: Symmetric Receive-only Advertised auto-negotiation: Yes Link partner advertised link modes: 10baseT/Half 10baseT/Full 100baseT/Half 100baseT/Full 1000baseT/Full Link partner advertised pause frame use: Symmetric Receive-only Link partner advertised auto-negotiation: Yes Speed: 1000Mb/s Duplex: Full Port: MII PHYAD: 0 Transceiver: internal Auto-negotiation: on Supports Wake-on: pumbg Wake-on: g Current message level: 0x00000033 (51) drv probe ifdown ifup Link detected: yes So why are the two machines seeing different "Link partner" settings? I tried Googling for "Link partner" but couldn't find anywhere that actually tells me what they mean, it *sounds* like it's what the 'other end' is advertising but from what I see above maybe it isn't. By the way I have tried changing the ethernet cable, no change at all. Can anyone elucidate things? -- Chris Green

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Back issues of Linux Format (97 Oct 07 - 127 Jan 10)
by Andrew Williams 19 May '12

19 May '12

Hello all. I'm having a clear out of some of my older Linux Format issues. Would anyone like them before I consign them to the recyling bin? Most DVDs also included. Cheers, Andrew.

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[ALUG Announce] 3rd Monday Monthly Ipswich Social Meeting : McGintys, Northgate Street ALUG ALUG
by samwise 18 May '12

18 May '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 ----- The monthly "Third Monday" ALUG Ipswich Social Meeting is back next week - Monday, 21st May, at 20:00: P J McGinty & Sons 15 Northgate Street Ipswich Suffolk IP1 3BY Tel: 01473 251 515 Map/Directions URI: http://maps.google.co.uk/?q=IP1+3BY WWW: http://www.pjmcgintys.co.uk/ McGintys pub is in the centre of Ipswich. It's directly opposite the town's central library and has a reputation for good Irish beer. We're usually to be found in the lowest section of the bar, near the library entrance to the pub. All are welcome, novices and experienced users. Feel free to ask for further information on the Main ALUG mailing list. Peter. ----- 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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Anyone managed to acquire a Raspberry Pi?
by Anthony Anson 15 May '12

15 May '12

-- Tony Anson www.girolle.co.uk/

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Some help with regex would be appreciated.
by Barry Samuels 14 May '12

14 May '12

I have to admit that apart from the simplest expressions I don't understand regex. I want to set up a logcheck ignore expression to ignore the following: kernel: [220359.596744] [drm] nouveau 0000:06:00.0: Setting dpms mode 0 on tmds encoder (output 2) The 220359.596744 number varies and so does the single mode digit, 0 in this instance, but the rest doesn't change. I have tried by copying some expressions parrot fashion but can't get it to work. Any help would be appreciated. -- Barry Samuels http://www.beenthere-donethat.org.uk The Unofficial Guide to Great Britain

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CD based Linux which works with FaceBook
by Ian Douglas 11 May '12

11 May '12

Hi playmates, My wife's laptop (Samsung R20) currently runs MS Windblows Vista and now takes so long to boot she can make a cup of tea while waiting (literally). I have found an old 2005 version of Knoppix laying around and she is amazed at how quick it is (running off the CD) but I was wondering if there is an even faster/leaner distro she could use. The distro must run off the CD and the browser must be capable of accessing Facebook (about all she uses the computer for!). Any suggestions welcome. Ian.

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Re: [ALUG] Cron oddity
by Mark Rogers 11 May '12

11 May '12

On 11/05/12 17:10, steve-ALUG(a)hst.me.uk wrote: > Cool. Hope it works for you. > Note this tho: > http://chrony.tuxfamily.org/FAQ.html#question_9.2 Noted, thanks. -- 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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Cron oddity
by Mark Rogers 11 May '12

11 May '12

I have a script which runs from cron every minute. I've added some logging to the script and I can see it starting reliably every minute, usually around 1s past the minute. So far so good. Occasionally (about 30 times yesterday) the script will also start within the minute, and looking at the logs there's some consistency to it - most (but not all) started at 47s past the minute. So I end up with: 21:31:01 Start 21:32:01 Start 21:32:47 Start 21:33:01 Start What could cause this? The only thing kicking the script off is cron. (It's running Debian Wheezy on ARM.) 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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Re: [ALUG] Inserting env vars or other data into config files
by Mark Rogers 11 May '12

11 May '12

On 09/05/12 17:59, Martijn Koster wrote: > I'd use a little script that greps for some markers to see if the file needs > changing (or already has been), and then apply the required changes with > diff/patch. How would I make a change like this using diff/patch? Eg: If I have a config file that says (real example from ssmtp): .... AuthUser=someuser AuthPass=somepass mailhub=somehost:587 ... .. and I want to set the values of someuser/somepass/somehost, what would the input to patch look like? (A pointer to relevant resources would be fine!) Is there a reason why patch would be preferable to sed for something like this? 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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