postinst is in fvwm-icons 20070101-3.
This file is a maintainer script. It is executed when installing (*inst) or removing (*rm) the package.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11  | #!/bin/sh
set -e
if [ "$1" = "configure" ]; then
    if [ -d /usr/doc ] &&
	[ -h /usr/doc/fvwm-icons ] &&
	[ -d /usr/share/doc/fvwm-icons ]
    then
        rm -f /usr/doc/fvwm-icons
    fi
fi
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