postrm is in unzip 6.0-21ubuntu1.
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 | #!/bin/sh
set -e
if which update-mime > /dev/null 2>&1; then
update-mime
fi
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