case in email addresses

The domain part (the part after @) is case-INSENSITIVE; the local mailbox part (the part before @) is case-SENSITIVE.

ext3 to ext4

To convert a partition from ext3 to ext4, do the following:

• enable ext4 features by running tune2fs -O extents,uninit_bg,dir_index /dev/DEV
• have fsck repair some inconsistencies that are created by the previous command e2fsck -fDC0 /dev/DEV
• (optional) mount the partition and force the kernel to rewrite all files by a command like this find /home -xdev -type f -print0 | xargs -0 chattr +e

Reminder: grub (v1) doesn’t support ext4, so if you upgrade your root (or /boot) partition, you need to chroot into your system and upgrade to grub2

Reminder2: if you can’t chroot (you get the error “cannot execute /bin/bash: exec format error”), it’s because you’re using a 32-bit livecd and are trying to chroot into a 64-bit system

References:

• https://ext4.wiki.kernel.org/index.php/Ext4_Howto
• http://wiki.archlinux.org/index.php/Ext4#Converting_ext3_Partitions_to_ext4

OO.o performance project

There’s a project trying to improve the performance of OpenOffice.org: http://wiki.services.openoffice.org/wiki/Performance

I found this while trying to find the cause of an issue I have: with OpenOffice 3.2, everytime I open a spreadsheet, after the splash screen completes, it waits for approx. 20 seconds doing nothing (no cpu or disk activity) and then opens the file. That happens even after closing and reopening the same file.

Opening just Calc (w/o a file) is very fast (~1 sec). If I then tell it to open a file, it hangs for 20 seconds like before. Removing the ~/.openoffice.org folder doesn’t help. Disabling Java in OO.o doesn’t help. Whether the file is .xls or .ods makes no difference. The same issue is present for .doc files

Using strace I found that it seems the call that make OO.o hang is the call to /bin/domainname

GeoIP

Had some fun today locating myself on various GeoIP sites:

• http://www.maxmind.com/app/locate_my_ip
• http://www.geoiptool.com/
• http://www.geobytes.com/ipLocator.htm
• http://www.hostip.info/
• http://www.ip2location.com/

Most are correct, only one thinks I’m in Berlin (hostip.info)

Fonts

https://wiki.ubuntu.com/Fonts (not of much help)

Three types of fonts:

1. http://en.wikipedia.org/wiki/OpenType (.otf) (Microsoft, Adobe) (ISO/IEC 14496-22)
2. http://en.wikipedia.org/wiki/TrueType (.ttf) (Apple)
3. http://en.wikipedia.org/wiki/PostScript_fonts (a.k.a Type1 fonts) (.afm/.pfb/.pfm) (Adobe)

x11 fonts???

http://www.openoffice.org/FAQs/fontguide.html

your fonts are under /usr/share/fonts

Backup

A list of backup solutions for Ubuntu:

generic
https://help.ubuntu.com/8.04/serverguide/C/backups.html
https://help.ubuntu.com/community/BackupYourSystem

hubackup (outdated, no longer available since jaunty)
https://help.ubuntu.com/8.04/keeping-safe/C/backup-files.html

sbackup (universe, last version 2008)
https://help.ubuntu.com/community/BackupYourSystem/SimpleBackupSuite
http://sourceforge.net/projects/sbackup/

duplicity (universe, active development)
https://help.ubuntu.com/community/DuplicityBackupHowto
http://www.nongnu.org/duplicity/index.html

backuppc (main, not so active)
https://help.ubuntu.com/community/BackupPC

bacula (main, active development)
https://help.ubuntu.com/community/Bacula
http://www.bacula.org/en/

rsnapshot (universe, last version 2008)
http://www.rsnapshot.org/

grsync
https://help.ubuntu.com/community/rsync

AptProxy

If you have a gateway and multiple Ubuntu machines, it might make sense to save bandwidth by using it (also) as an proxy server for apt. Here’s some useful links:

• https://help.ubuntu.com/community/AptProxy
• http://apt-proxy.sourceforge.net/
• http://sourceforge.net/projects/apt-proxy/ (stuck at 1.9.36 since hardy)
• https://help.ubuntu.com/community/Apt-Cacher-Server
• http://www.nick-andrew.net/projects/apt-cacher/
• http://www.porcheron.info/bandwith-optimization-squid-apt-cacher-and-jesred/

openoffice bibliography database

Every OpenOffice.org user has a bibliography database, located under ~/.openoffice.org/3/user/database/biblio.odb

There’s a bug where if you don’t have OO.o Base installed and click on Tools->Bibliography Database, OpenOffice will crash (didn’t anyone test this before release?).

Another issue could be that the “Title” field has a max. length of 75 characters, which is too short for some papers.

chroot

To install/remove packages (or modify in general) on a Linux system that is unbootable, you can boot with a LiveCD, mount the underlying system’s root partition and then chroot to that mount point. After that, any commands will be run on the underlying system, rather than on the LiveCD…

Some actions (e.g. installing grub) require also the devfs, procfs and sysfs filesystems, so before chrooting, remember to also:

• sudo mount -o bind /dev /mnt/dev
• sudo mount -t proc none /mnt/proc
• sudo mount -t sysfs none /mnt/sys

(I assume here that the root partition was mounted under /mnt)

Update 01.10.2010: if you’re using dhcp, networking will not work because /etc/resolv.conf will be empty. Add “nameserver 8.8.8.8″ to that file

EC document formats

The document formats supported by the European Commission for “information providers”:

http://ec.europa.eu/ipg/standards/document/index_en.htm