Check bugs in Debian and seek help
If you are experiencing problems regarding a specific package, make sure to check out these sites first before you seek help or before you file a bug report. (lynx, links, and w3m work equally well):
$ lynx http://bugs.debian.org/
$ lynx http://bugs.debian.org/package-name # if you know package name
$ lynx http://bugs.debian.org/bugnumber # if you know bug number
Search Google (www.google.com) with search words including "site:debian.org".
When in doubt, read the fine manual. Set CDPATH as follows:
export CDPATH=.:/usr/local:/usr/share/doc
and type
$ cd packagename
$ pager README.Debian # if this exists
$ mc
APT upgrade troubleshooting
Package dependency problems may occur when upgrading in unstable/testing . Most of the time, this is because a package that will be upgraded has a new dependency that isn't met. These problems are fixed by using
# apt-get dist-upgrade
If this does not work, then repeat one of the following until the problem resolves itself:
# apt-get upgrade -f # continue upgrade even after error
... or
# apt-get dist-upgrade -f # continue dist-upgrade even after error
Some really broken upgrade scripts may cause persistent trouble. It is usually better to resolve this type of situation by inspecting the /var/lib/dpkg/info/packagename.{post,pre}{inst,rm} scripts of the offending package and then running:
# dpkg --configure -a # configures all partially installed packages
If a script complains about a missing configuration file, look in /etc/ for the corresponding configuration file. If one exists with an extension of .new (or something similar), change (mv) it to remove the suffix.
Package dependency problems may occur when installing in unstable/testing. There are ways to circumvent dependency.
# apt-get install -f package # override broken dependencies
An alternative method to fix these situations is to use the equivs package. See /usr/share/doc/equivs/README.Debian and The equivs package,
Rescue using dpkg
Ad hoc recovery of a crashed dselect (APT) can be done on a really broken system by just using dpkg without APT:
# cd /var/cache/apt/archives
# dpkg -i libc6* libdb2* perl*
# dpkg -i apt* dpkg* debconf*
# dpkg -i * # until no error occurs
If a package is missing, get it from mirror sites by:
# mc # use "FTP link" pointing to Debian FTP server
As of recently, actual packages on the HTTP/FTP server may not be located under the classic /dist directory but rather under the new /pool directory.
Then install by:
# dpkg -i /var/cache/apt/archives/packagefile.deb
For a broken dependency, fix it or use:
# dpkg --ignore-depends=package1,... -i packagefile.deb
# dpkg --force-depends -i packagefile.deb
# dpkg --force-depends --purge package
# dpkg --force-confmiss -i packagefile.deb # Install missing conffile
Recover package selection data
If /var/lib/dpkg/status becomes broken for any reason, the Debian system loses package selection data and suffers severely. Look for the old /var/lib/dpkg/status file at /var/lib/dpkg/status-old or /var/backups/dpkg.status.*.
Keeping /var/backups/ in a separate partition may be a good idea since this directory contains lots of important system data.
If the old /var/lib/dpkg/status file is not available, you can still recover information from directories in /usr/share/doc/.
# ls /usr/share/doc | \
grep -v [A-Z] | \
grep -v '^texmf$' | \
grep -v '^debian$' | \
awk '{print $1 " install"}' | \
dpkg --set-selections
# dselect --expert # reinstall system, de-select as needed
Rescue system after crashing /var
Since the /var directory contains regularly updated data such as mail, it is prone to be corrupted. Separating it in an independent partition limits risks. If disaster happens, you may have to rebuild the /var directory to rescue your Debian system.
Obtain the skeleton content of the /var directory from a minimum working Debian system based on the same or older Debian version, for example var.tar.gz, and place it in the root directory of the broken system. Then
# cd /
# mv var var-old # if any useful contents are left
# tar xvzf var.tar.gz # use Woody skeleton file
# aptitude # or dselect
This should provide a working system.
Install a package into an unbootable system
Boot into Linux using a Debian rescue floppy/CD or an alternative partition in a multiboot Linux system. . Mount the unbootable system on /target and use the chroot install mode of dpkg.
# dpkg --root /target -i packagefile.deb
Then configure and fix problems.
By the way, if a broken lilo is all that prevents booting, you can boot using a standard Debian rescue disk. At boot prompt, assuming the root partition of your Linux installation is in /dev/hda12 and you want runlevel 3, enter:
boot: rescue root=/dev/hda12 3
Then you are booted into an almost fully functional system with the kernel on floppy disk. (There may be minor glitches due to lack of kernel features or modules.)
What to do if the dpkg command is broken
A broken dpkg may make it impossible to install any .deb files. A procedure like the following will help you recover from this situation. (In the first line, you can replace "links" with your favorite browser command.)
$ links http://http.us.debian.org/debian/pool/main/d/dpkg/
... download the good dpkg_version_arch.deb
$ su
password: *****
# ar x dpkg_version_arch.deb
# mv data.tar.gz /data.tar.gz
# cd /
# tar xzfv data.tar.gz
For i386, http://packages.debian.org/dpkg may also be used as the URL.
