postinst is in needrestart-session 0.3-5.
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 12 13 14 15 16 17 18 19 | #!/bin/sh
set -e
case "$1" in
        configure)
                adduser --system --no-create-home --home /nonexistent --quiet needrestart-dbus || true
        ;;
        abort-upgrade|abort-remove|abort-deconfigure)
        ;;
        *)
                echo "postinst called with unknown argument \`$1'" >&2
                exit 1
        ;;
esac
exit 0
 |