Ubuntu – always purge on remove in package

aptdpkgpackage-managementpackaging

I am maintaining a debian package, which includes some config files that are installed under /etc/. Is there a way I can somehow make the package to always automatically --purge itself whenever a user does a regular apt-get remove mypackage ?

The reason is that I have some config files in /etc that should really be removed when the binaries are removed, otherwise it can lead to weird behavior. However I still want to treat them as conf files, i.e. make sure apt does not just wipe them on every upgrade of the package. But they should be removed when the package is uninstalled.

Currently I am manually deleting the /etc conf files in my postrm script. However I just found out that this has a unfortunate side effect: if the user uninstalls and then later re-installs the package, the conf files won't be reinstalled, because apt thinks that they are still there. So is there a way I can manually trigger a full 'purge' in my postrm, such that apt knows that the conf files are gone?

Best Answer

The debian policy forbids you from messing around with files that belong to other packages and/or system changes. (or at least I think it does)

Teach your users

You may instruct users to use purge instead of remove:

sudo apt-get purge mypackage

Automatic overwrite

If you need to overwrite configuration files, debian may prompt the user to install the maintainer configuration files: http://www.debian.org/doc/manuals/maint-guide/dother.en.html#conffiles

One of the most annoying things about software is when you spend a great deal of time and effort customizing a program, only to have an upgrade stomp all over your changes. Debian solves this problem by marking such configuration files as conffiles. [55] When you upgrade a package, you'll be asked whether you want to keep your old configuration files or not.

Force new configuration files by default

You may do that automatically while upgrading:

apt-get -o Dpkg::Options::="--force-confnew" dist-upgrade

Sources: http://raphaelhertzog.com/2010/09/21/debian-conffile-configuration-file-managed-by-dpkg/ and https://askubuntu.com/a/104912/5538

Provides/Conflicts/Replaces

I'm not sure about this, but I think you may can fully purge and replace an old package version with a new package version.

Read here: http://www.debian.org/doc/debian-policy/ch-relationships.html#s-replaces

Related Solutions

Ubuntu – What happens during a package upgrade

The debian wiki is pretty much usefull to understand the process (which is explained in details here).

For example :

the case of a simple installation of package
- the case of a the upgrade of a package

enter image description here

Ubuntu – How to run a script only during first install of a package and not during upgrades

With a debian/preinst file you can perform actions on install but not upgrade.

#!/bin/sh
set -e

case "$1" in
    install)
        # do some magic
        ;;

    upgrade|abort-upgrade)
        ;;

    *)
        echo "postinst called with unknown argument \`$1'" >&2
        exit 0
        ;;
esac

#DEBHELPER#

exit 0

Though as the name implies, this is run before your package is installed. So you might not be able to do what you need here. Most packages simply test in the configure stage of the postinst if the user has been created already. Here's colord

$ cat  /var/lib/dpkg/info/colord.postinst
#!/bin/sh

set -e

case "$1" in
    configure)

# create colord group if it isn't already there
    if ! getent group colord >/dev/null; then
            addgroup --quiet --system colord
    fi

# create the scanner group if it isn't already there
    if ! getent group scanner >/dev/null; then
        addgroup --quiet --system scanner
    fi

# create colord user if it isn't already there
    if ! getent passwd colord >/dev/null; then
            adduser --system --ingroup colord --home /var/lib/colord colord \
        --gecos "colord colour management daemon"
        # Add colord user to scanner group
        adduser --quiet colord scanner
    fi

# ensure /var/lib/colord has appropriate permissions
    chown -R colord:colord /var/lib/colord

    ;;
esac    



exit 0