postinst is in ccache 3.2.4-1.
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 | #!/bin/sh
set -eu
echo "Updating symlinks in /usr/lib/ccache ..."
update-ccache-symlinks
|