Maintain /etc with mercurial on Debian
Update on 2007-09-12: updated shell script and added Pre-Invoke to dpkg configuration.
Based on Bart Trojanowski’s blog article “etc snapshots with git” I removed one further item from my todo list: maintain /etc with mercurial on my Debian systems.
First step is creating the repository and securing access to the repository. As mercurial stores all its files within one single directory named .hg you won’t have any further directories within /etc besides /etc/.hg, rocking – right? ;-)
cd /etc hg init chmod og-rwx .hg
Ignore a few files:
cat > .hgignore << EOF syntax: regexp (^)*.dpkg-new (^)*.dpkg-old (^)blkid.tab(|.old) (^)mtab # add other files if necessary, depends on your setup... EOF
Now commit the current state:
hg add hg ci -m "initial checkin"
We want to commit the changes automatically when using apt-get/aptitude so let’s write and include a wrapper for it – /etc/apt/hg-snapshot-script:
#!/bin/sh
set -e
caller=$(ps axww | mawk '/aptitude|apt-get/ {for (i=5; i<=NF ; i++) printf ("%s ",$i); printf ("\\n") }' | head -1)
hg addremove 1>/dev/null
STATUS="$(hg st)"
if [ -z "$STATUS" ] ; then
echo "hg-snapshot-script: nothing to be done"
else
case "$1" in
pre)
echo "hg-snapshot-script: found changed files:"
hg st
hg ci -m "snapshot from $LOGNAME before: $caller"
;;
post)
echo "hg-snapshot-script: found changed files:"
hg st
hg ci -m "snapshot from $LOGNAME after: $caller"
;;
*)
echo "hg-snapshot-script: found changed files:"
hg st
hg ci -m "snapshot from $LOGNAME on $(date '+%Y-%m-%d - %H:%M:%S')"
;;
esac
fi
Activate it:
chmod +x /etc/apt/hg-snapshot-script
cat >> /etc/apt/apt.conf << EOF
DPkg {
Pre-Invoke {"cd /etc ; ./apt/hg-snapshot-script pre";};
Post-Invoke {"cd /etc ; ./apt/hg-snapshot-script post";};
}
EOF
Finally track the added files as well:
hg add hg commit -m "apt will track /etc automagically using hg"
That’s it. :-)
Oh BTW: users of subversion might want to point their browser to /etc under svk (by Enrico Zini).