purge-var-cache-zypp.sh

#!/bin/bash

# OpenSUSE zypper - Purge off any /var/cache/zypp rpms that are not installed in this system

if [ $# -ne 0 -a "$1" != "--report-only" -a "$1" != "--purge" ]
then
    >&2 echo "ERROR: invalid argument $1 - valid arguments are --report-only or --purge"
    exit 1
fi

>&2 echo "INFO: usage before $(du -h -s /var/cache/zypp)"

cd /var/cache/zypp && find . -type f -name '*.rpm' | gawk '
    BEGIN {
        # Use rpm to initialise a hash table of all installed rpms
        rpm_cmd = "rpm -q -a"
        while ((rpm_cmd | getline) > 0) {
            rpm_index[$0] = 1;
        }
        status = close(rpm_cmd);
        if (status) {
            print "ERROR: error running ", rpm_cmd, ERRNO > "/dev/stderr";
            exit 1;
        }
        if (length(rpm_index) < 1000) {
            print "ERROR: too few rpms are installed, probably an error, cowardly refusing to continue ", length(rpm_index) ERRNO > "/dev/stderr";
            exit 1;
        }
        # Change field separator to / to ease extracting the filename only
        FS = "/";
    }
    {
        # For each file reported by find, check if it is not in the hash table
        name_only = $NF;
        sub(".rpm$", "", name_only);
        if (!rpm_index[name_only]) {
            # Output filenames to xargs to reduce the number of execs of rm to the mininum required.
            print $0;
        }
    }
    ' | if [ $# -eq 0 -o "$1" == "--report-only" ] 
    then
        >&2 echo "WARN: reporting only, no space will be recovered" 
        cat 
    elif [ "$1" == "--purge" ]
    then
        >&2 echo "WARN: commencing purge" 
        xargs --no-run-if-empty rm
        >&2 echo "INFO: usage after  $(du -h -s /var/cache/zypp)"
    fi

exit 0