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ssh problem, why can't I public-key authenticate to one particular login?
by Chris G 12 Apr '11

12 Apr '11

I want to be able to become www-data on my desktop machine so I can edit HTML files etc. directly without problems. So I have tried to set up a passwordless ssh login to www-data but I can't get it to work. Doing identical things to another login works perfectly. Before using ssh-copy-id :- chris$ ssh -l zelma chris zelma@chris's password: zelma@chris:~$ exit logout Connection to chris closed. chris$ ssh -l www-data chris www-data@chris's password: www-data@chris$ exit logout Connection to chris closed. chris$ Use ssh-copy-id to set up both logins:- chris$ ssh-copy-id zelma@chris zelma@chris's password: Now try logging into the machine, with "ssh 'zelma@chris'", and check in: .ssh/authorized_keys to make sure we haven't added extra keys that you weren't expecting. chris$ ssh-copy-id www-data@chris www-data@chris's password: Now try logging into the machine, with "ssh 'www-data@chris'", and check in: .ssh/authorized_keys to make sure we haven't added extra keys that you weren't expecting. chris$ It works to 'zelma' but not to 'www-data' :- chris$ ssh 'zelma@chris' zelma@chris:~$ exit logout Connection to chris closed. chris$ ssh 'www-data@chris' www-data@chris's password: www-data@chris$ exit logout Connection to chris closed. chris$ So there's something different about www-data but what is it? There's nothing special in the sshd_config file and I've completely removed both zelma's and www-data's ~/.ssh directories before starting the above. Any ideas/suggestions anyone? -- Chris Green

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Blogging software that can be 'filtered' - any ideas?
by Chris G 12 Apr '11

12 Apr '11

I think I'm looking for some blog software (more to use for keeping tabs on my thoughts and as an aide memoire than for inviting comments) but I'd really like to be able to 'filter' the blog. I.e. I'd like to be able to tag entries in the blog with tags such as 'boat', 'motorbike', etc. and then have the ability to view the blog as a 'boat' blog or a 'motorbike' blog showing only the boat or motorbike tagged pages. One approach of course is simply to have separate blogs for each but it's also possible there will be overlapping tags and it would also be useful to see the whole blog at times. Any ideas if there's anything out there that can do this? If one could actually set the 'current tag' for a session that would be ideal. -- Chris Green

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[ALUG Announce] ALUG Norwich Pub Meet Thurday 14th April
by Viperfang 11 Apr '11

11 Apr '11

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 Aluggers, Our monthly ALUG Norwich social meeting will be held this Thursday, 14th April 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 OFTC (irc.oftc.net) 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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Cheap netbooks
by mick 05 Apr '11

05 Apr '11

Guys I know that some people on this list have expressed interest in cheap netbooks in the past. I have just noticed that Morgan computers are shipping refurbished HP Mini 110s (intel atom CPU, 1Gig ram, 250Gig hdd) for a very reasonable £175.00 inc VAT. OK, they have windows 7 installed, but that is fixable. (They also have the Acer netbook with windows 7 for £194.00 which they offer to "upgrade to Ubuntu 10.10" for ten quid!) Mick --------------------------------------------------------------------- The text file for RFC 854 contains exactly 854 lines. Do you think there is any cosmic significance in this? Douglas E Comer - Internetworking with TCP/IP Volume 1 http://www.ietf.org/rfc/rfc854.txt ---------------------------------------------------------------------

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Mini-itx case
by David Reynolds 04 Apr '11

04 Apr '11

Anyone have any interest in a Cubid 2699R mini-itx case? -- David Reynolds david(a)reynoldsfamily.org.uk

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Strange mount problem, now fixed but I don't understand why
by Chris G 01 Apr '11

01 Apr '11

I have a 750Mb external hard disk that I use for temporary backups, moving stuff from system to system, etc. I has both eSata and USB interfaces. Yesterday I tried to use it to copy some files off my linux based WD NAS. I couldn't mount it:- root@backup# mount -n -t ext3 /dev/sdc1 /usbdisk mount: Mounting /dev/sdc1 on /usbdisk failed: Invalid argument (adding/removing the -n or -t options made no difference) Running fdisk on the drive showed the following:- Disk /dev/sdc: 750.1 GB, 750156374016 bytes 255 heads, 63 sectors/track, 91201 cylinders Units = cylinders of 16065 * 512 = 8225280 bytes Device Boot Start End Blocks Id System /dev/sdc1 1 91201 732572001 83 Linux So I re-partitioned the disk with fdisk and recreated the file system with mke2fs. Now fdisk -l reports:- Disk /dev/sdc: 750.1 GB, 750156374016 bytes 255 heads, 63 sectors/track, 91201 cylinders Units = cylinders of 16065 * 512 = 8225280 bytes Device Boot Start End Blocks Id System /dev/sdc1 1 91201 732572001 83 Linux Which is identical to what it reported before. However the disk now mounts successfully! root@backup# mount -n -t ext3 /dev/sdc1 /usbdisk root@backup# So what's different? I guess it must be something to do with the file system created by mke2fs. -- Chris Green

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Re: [ALUG] Using rsync --link-dest continued, comments welcome
by Phil Ashby 01 Apr '11

01 Apr '11

Chris G <cl(a)isbd.net> wrote: > Well here's my initial attempt at writing the incremental backup using > rsync's --link-dest :- > ...[weekly rotating backup script] I got this going on my file server (not a NAS - it's a Debian box) using the following script, which can be executed at any interval that seems appropriate*, and retains a specified quantity of previous backups rather than a time limited number. I find that so little changes between backups that I can keep 100 of them on the same size backup media as the main storage (1TB, ~60% full). This should work in ash almost as-is, but you may need to use dc for the maths (subtracting 1) instead of shell built-in capability: TGT=`echo $BKP 1 -pq|dc` Notes: - This keeps the backup device mounted read-only unless a backup is in progress, to avoid 'finger trouble' nuking important stuff. - Uses the noatime option when mounted rw, to improve performance. - Since this is a full file system backup, it excludes rather than includes folders. - It doesn't try to back up if there is <10G of free space on the backup device (empirical determination, typically I see 10-20G of change at worst per backup). - Error messages (and debug) to stderr as this is run by cron so will get emailed to root (me). - Any issues are collected and stored in the backup folder. Phil. * - currently every 4 hours during the day but not overnight since the machine may be busy using my free overnight bandwidth :) ----8<---- #! /bin/sh # Take a snapshot of the current filesystem (minus snapshot folder and caches) #DBG=--verbose BACKUP_DEV="UUID=go-look-in-dev-disk-by-uuid-xxxxxxxxxxxx" BACKUP_DIR=/var/backups/snapshot EXCLUDES="/dev /proc /sys /mnt /media /tmp /var/cache /var/lock \ /var/www/.get_iplayer $BACKUP_DIR" # Time/date records BKSTART=`date` # Only keep up to 100 snapshots MAX_BACKUP=100 # 10GB in k MIN_SPACE_K=10000000 docmd() { [ -n "$DBG" ] && echo debug: "$*" >&2 $* } NEED_REMOUNT= remount() { docmd mount -o remount,ro $BACKUP_DEV $BACKUP_DIR } barf() { echo "$*" >&2 [ -n "$NEED_REMOUNT" ] && remount exit 1 } # Mount the snapshot folder read-write docmd mount -o remount,rw,noatime $BACKUP_DEV $BACKUP_DIR [ $? -eq 0 ] || barf "unable to remount $BACKUP_DIR rw" NEED_REMOUNT=1 # Space check docmd cd $BACKUP_DIR AVAIL=`df -k . |tail -1 |(read d b u a t; echo $a)` [ $AVAIL -gt $MIN_SPACE_K ] || barf "out of backup device space" [ -n "$DBG" ] && echo "debug: available space: ${AVAIL}k" >&2 # Rotate existing backups [ -d backup.$MAX_BACKUP ] && docmd rm -rf backup.$MAX_BACKUP BKP=$MAX_BACKUP while [ $BKP -gt 0 ] do TGT=$(($BKP-1)) [ -d backup.$TGT ] && docmd mv backup.$TGT backup.$BKP BKP=$TGT done # rsync changes into fresh backup, hard-linking unchanged files for p in $EXCLUDES do echo $p >>/tmp/backup-excludes.$$ done docmd rsync $DBG -a --link-dest=$BACKUP_DIR/backup.1 --exclude-from=/tmp/backup-excludes.$$ / $BACKUP_DIR/backup.0 >/tmp/sync-log.$$ 2>&1 if [ $? -ne 0 ]; then echo "rsync into $BACKUP_DIR had some problems, see log" >&2 docmd mv /tmp/sync-log.$$ $BACKUP_DIR/backup.0/RSYNC.LOG fi docmd rm -f /tmp/backup-excludes.$$ /tmp/sync-log.$$ # Time/date records BKSTOP=`date` docmd echo "Backup started: $BKSTART, completed: $BKSTOP" >$BACKUP_DIR/backup.0/README.DATES # Remount read-only NEED_REMOUNT= remount [ $? -eq 0 ] || barf "unable to remount $BACKUP_DIR ro"

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date command error
by James Bensley 31 Mar '11

31 Mar '11

Can anyone explain this? [user@machine ~]$ date Tue Mar 29 16:48:38 BST 2011 [user@machine ~]$ date --date="1 month ago" Tue Mar 1 15:48:47 GMT 2011 Shouldn't that last one say the date one month ago, not 28 days ago? (I suppose one month needs to be quantified). Not sure how 'date' has worked that out but I'm guessing the change in time zone might perhaps be to blame? Can anyone shed some light on this? -- James. http://www.jamesbensley.co.cc/ There are 10 kinds of people in the world; Those who understand Vigesimal, and J others...?

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Using rsync --link-dest continued, comments welcome
by Chris G 31 Mar '11

31 Mar '11

Well here's my initial attempt at writing the incremental backup using rsync's --link-dest :- #!/bin/ash # # # Backup script run daily # dirs="chris dps laptop" today=`date +%a` case $today in "Sun") yesterday="Sat";; "Mon") yesterday="Sun";; "Tue") yesterday="Mon";; "Wed") yesterday="Tue";; "Thu") yesterday="Wed";; "Fri") yesterday="Thu";; "Sat") yesterday="Fri";; esac for dir in $dirs do # # # remove last week's backup # rm -fr /ExtendVolume/$dir/$today # # # Run rsync to create a new backup for today # rsync -a --link-dest=/ExtendVolume/$dir/$yesterday /DataVolume/$dir/ /ExtendVolume/$dir/$today done It works to the extent that it's creating the backup for 'today' on /ExtendVolume, I'll have to wait until tomorrow before I can tell if it's doing the hard links right. I get a warning error today of course:- --link-dest arg does not exist: /ExtendVolume/chris/Wed but that's fine, it's actually quite encouraging! :-) If anyone can suggest a better way of working out 'yesterday' than that horrible case sequence I'd love to see it. While the case works it grates rather when I look at it! (It has to be in ash or sh, the NAS doesn't have bash or similar) -- Chris Green

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Anyone know anything about rsync --link-dest option usage?
by Chris G 31 Mar '11

31 Mar '11

I'm aiming to use rsync's --link-dest option to do some incremental backups but I'm not absolutely sure I've got its use correct. What I'm going to do is maintain incremental backups for the last seven days, so they'll be in directories named for the days of the week. The script will work out values for today and yesterday and then do (example for today):- rm -fr /backup/Wed rsync -a --link-dest=/backup/Tue fromSource /backup/Wed Will this do what's intended? I'm less interested in detailed syntax errors but want to be sure I will get 7 days of incremental backups. -- Chris Green

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