January 2013 - main

Centos - anyone use it?
by James Freer 31 Jan '13

31 Jan '13

Just out of interest i was wondering if many folk on here use Centos. I've decided now to stop using *buntu after 5 years. I've had a few gripes with *buntu in the past and two bugs in xubuntu i found in (im)Precise - time for a change. Besides that i've been wondering why some packages are being left out - apparently dpkg have changed their description fields and if the author doesn't amend they are left out. *buntu seem to be going on a downhill slide in lots of areas and before unity. james

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Bit off topic
by Anthony Anson 31 Jan '13

31 Jan '13

I have several chargers with different rates of delivery: has anyone any idea where I should start looking for data relating to recharging NiCad and Nion batteries? Like: Output of charger Time to charge per mA capacity of each type of battery Or a way to calculate time, allowing for (expected) losses in the process. No, I'mnot being (very) lazy. On this GPRS connection a thorough websearch is time-consuming, and, at £15 per Gig. expensive. -- Tony

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Thunderguts
by Anthony Anson 31 Jan '13

31 Jan '13

Not sure if my reply to Chris Walker was sent - tried twice. Thunderwotsit wouldn't send to the 'Sent' folder, and the message remained on screen. May be due to the Vogonfone connection, which may be dropping out. -- Tony

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2600 meeting at 18:00 on Friday the 1st February.
by Viperfang 29 Jan '13

29 Jan '13

Quick heads up about this months Norwich 2600 meeting, more info at http://www.norwich2600.co.uk

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Re: [ALUG] Testing 5V USB supplies for RPi usage
by Phil Ashby 28 Jan '13

28 Jan '13

On 28/01/13 12:00, Mark Rogers <mark(a)quarella.co.uk> wrote: > On 27 January 2013 01:04, Anthony Anson <tony.anson(a)girolle.co.uk> wrote: >> Have a look at www.maplin.co.uk/ and see if (offers) N66JU; A92JH; A83LA >> float your boat. > > Just to make it clear (because I don't think I did from the outset), > it's not that I'm having a problem sourcing supplies that will keep > the RPi going - I have some that do and some that don't, it's that the > current method of testing (plug it in and see whether it crashes) is a > bit inexact, and the correct method (read the label to see what > current it's rated at) isn't working because the labels can't be > trusted on some of them. > > Also, there's the option of complaining and getting a refund on ones > that are no good, and having a measurement to back me up always helps. > And finally, perhaps more importantly for me, its the opportunity to > learn how to get the measurement. Sounds like a job for a dummy load and a voltmeter? Unless the crash isn't down to sustained low voltage but surge capability, dunno if the Pi has a current surge rating. There is a nice write up here: http://elinux.org/RPi_Hardware#How_Can_I_tell_if_the_power_supply_is_inadeq… Phil.

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Testing 5V USB supplies for RPi usage
by Mark Rogers 28 Jan '13

28 Jan '13

I have several 5V USB supplies, which if the labels on them are to be believed will supply anything from 1 to 2.5A, although I have serious doubts that I can believe the labels. Based on how sowly they charge my phone I think some that are labelled 2.5A are more like 200mA... They're from various sources, which include the likes of eBay. Some will power my RPi, but only if I don't try to plug in a USB device as well. Assuming very little in the way of electrical knowledge (which I guess is obvious as I don't know the answer to my question), what's the "best" way to see what current a power supply can deliver? I have a multimeter, and could doubtless obtain some resisters (or other components) if I need to. I also have a shiny new temperature controlled soldering iron that's never been used if that helps :-) -- Mark Rogers // More Solutions Ltd (Peterborough Office) // 0844 251 1450 Registered in England (0456 0902) @ 13 Clarke Rd, Milton Keynes, MK1 1LG

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Re: [ALUG] Colour Laserjet printer problem
by Barry Samuels 28 Jan '13

28 Jan '13

On 25/01/13 22:13:44, Jenny Hopkins wrote: > On 25 January 2013 16:33, Barry Samuels > <bjsamuels(a)beenthere-donethat.org.uk> wrote: > > I have an HP Colour LaserJet 4500 and recently it displayed a message > > to the effect that the black (K) toner was low. I have configuration > > set to continue until toner runs out but before that happened it > > started to show grey bands vertically down the page. < snip> > I changed my HP printer black cartridge the other day and it still > only printed grey faded stuff, so I used "sudo hp-clean" provided by > hplip package, ran clean twice from the gui that popped up, and all > was well (debian 6). > > Jenny I think that that is applicable only to inkjet printers and mine is a laser but thank you for trying. -- Barry Samuels http://www.beenthere-donethat.org.uk The Unofficial Guide to Great Britain

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udev and hdparm
by Barry Samuels 28 Jan '13

28 Jan '13

I have two sata backup drives which I use for daily rsync backups. As the drive is running for a relatively short time during the night I don't want it rotating for the rest of the time. hdparm -S 12 /dev/sdb will set the spindown to 1 minute after the last use and that works from the command line. However I would like the command to be automatically given when the drive is inserted and reading on the Internet suggests using UDEV. I've put this in a .rules file: # Set spindown time for backup drive when inserted. KERNEL=="sdb", RUN+="/sbin/hdparm -S 12 /dev/sdb" But that doesn't work i.e. nothing happens. When I first tried I put only one = after KERNEL and UDEV complained so I know it is being 'seen' and the drive is always 'sdb'. Should it work? -- Barry Samuels http://www.beenthere-donethat.org.uk The Unofficial Guide to Great Britain

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Colour Laserjet printer problem
by Barry Samuels 25 Jan '13

25 Jan '13

I have an HP Colour LaserJet 4500 and recently it displayed a message to the effect that the black (K) toner was low. I have configuration set to continue until toner runs out but before that happened it started to show grey bands vertically down the page. I decided to change the toner in the hope that it might cure the problem but it didn't. I can see rings of toner around the imaging drum if I take it out. It does seem to be picking up surplus toner but I've no idea where from. At present I have: Transfer Kit showing 96% life left Fuser Kit showing 91% life left Drum Kit 68% lif left Any suggestions would be appreciated. If you suggest cleaning something would you please explain where to find it because I probably won't know. -- Barry Samuels http://www.beenthere-donethat.org.uk The Unofficial Guide to Great Britain

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MySQL select into
by Mark Rogers 22 Jan '13

22 Jan '13

Any MySQL gurus here? I have a table: `item_uid` INT (Primary key) `cat_uid` INT <several other fields> What I want to do is take all records where cat_uid=10, and insert them back into the table with cat_uid=11 (in other words duplicating "category 10" as "category 11". What I had was: CREATE TEMPORARY TABLE tmp SELECT * FROM myTable WHERE cat_uid=10; UPDATE tmp SET cat_uid=11; INSERT INTO myTable SELECT * FROM tmp; This used to work when I didn't have the primary key `uid`, but now this just attempts to insert duplicates for the uid field and fails. The following works instead: CREATE TEMPORARY TABLE tmp SELECT * FROM myTable WHERE cat_uid=10; ALTER TABLE tmp CHANGE uid uid INT(11) NULL DEFAULT NULL; UPDATE tmp SET uid=NULL, cat_uid=11; INSERT INTO myTable SELECT * FROM tmp; In other words, alter the tmp table structure to allow the uid field to be NULL, and as part of my update set all the uid's to NULL, so that the final insert tries to insert NULL for uid which causes MySQL to insert the next auto-increment value instead. But this seems very convoluted, is there a "correct" (or just "better") way? -- Mark Rogers // More Solutions Ltd (Peterborough Office) // 0844 251 1450 Registered in England (0456 0902) @ 13 Clarke Rd, Milton Keynes, MK1 1LG

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