Computers Linux

Control Debian daemons

Debian and Ubuntu place startup files for all deamons in /etc/init.d. Symbolic links are then placed in /etc/rc.X to control when deamons are to be started and stopped. While it would certainly be possible to manage it manually, there are a few tools that makes life easier whenever you want to control which daemons are started by default.

Using rcconf


Using sysv-rc-conf


Using update-rc.d

usage: update-rc.d [-n] [-f]  remove
       update-rc.d [-n]  defaults|multiuser [NN | sNN kNN]
       update-rc.d [-n]  start|stop NN runlvl [runlvl] [...] .
		-n: not really
		-f: force

Computers Linux

Keeping track of installed apps, part 2

In an earlier post I wrote how to output a list the currently installed applications under Debian (and distributions based upon it). This will now be extended into a script that can be run each hour to record changes to the installed applications. Now, it should be said from the beginning that this information may already be stored in the file /var/log/apt/term.log but it can be a challenge to follow what it happening.

The following script stores a snapshot of the installed applications and then makes a diff against that on a period basis (e.g. by running it as an hourly cron job). If there is a difference, the changes are saved to a time stamped file and a new snapshot is taken. All files are placed in the same log directory as apt normally uses (i.e. /var/log/apt). The downside of this method is that changes will be recorded with a granularity of an hour but usually that is not an issue as the reason for writing this was to keep an automated record of changes to the system.

if [ ! -e $installed ]; then
  echo "Creating initial file"
  dpkg-query -W -f='${Package}\n' > $installed
  cp $installed $folder'initial'
# Compare package list against current
dpkg-query -W -f='${Package}\n' | diff $installed - \
  | grep -e '^[(<|>)]' > /dev/null
if [ $? -eq 0 ]; then
  # The set of installed packages has changed. Save the delta to a
  # file and save the new snapshot
  filename=$folder`date +%Y-%m-%d_%H-%M-%S`
  dpkg-query -W -f='${Package}\n' | diff $installed - \
    | grep -e '^[(<|>)]' > $filename
  dpkg-query -W -f='${Package}\n' > $installed
exit 0

Computers Linux

Keeping track of installed apps under Debian

I am setting up my new server with Ubuntu 8.10. This time, I am planning to keep track on all the software I install on it so that I might restore it in the future. Thankfully, with the Debian package manager this is a simple task.

The following command creates a text file with all the installed applications on the system:

dpkg-query -W -f='${Package\n}' > installed-apps

The file will put one one package name on a line and end it with a line break, saving the output to the file installed-apps. By changing the \n at the end into a space it is possible to get a single long string with all the package names.

After a while you may want to know which packages have been installed since the initial operating system installation. There are no doubt many ways of doing this but the easiest I have come up with is to run the same command as above, but save the output to another file, and then to run ‘diff’ on those two files. Note that this requires that the output from the dpkg-query command above was using line breaks to separate packages.