postinst is in apt-mirror 0.5.4-1.
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 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 | #!/bin/sh
set -e
setup_aptmirror_user() {
	if ! id apt-mirror > /dev/null 2>&1; then
		adduser --quiet --system --group --no-create-home --home /var/spool/apt-mirror --shell /bin/sh apt-mirror
	fi
}
setup_aptmirror_clean() {
	touch /var/spool/apt-mirror/var/clean.sh
	touch /var/spool/apt-mirror/var/postmirror.sh
	chmod +x /var/spool/apt-mirror/var/clean.sh
}
set_aptmirror_owner() {
	chown apt-mirror:apt-mirror /var/spool/apt-mirror
	chown apt-mirror:apt-mirror /var/spool/apt-mirror/mirror
	chown apt-mirror:apt-mirror /var/spool/apt-mirror/skel
	chown apt-mirror:apt-mirror /var/spool/apt-mirror/var
	chown apt-mirror:apt-mirror /var/spool/apt-mirror/var/clean.sh
	chown apt-mirror:apt-mirror /var/spool/apt-mirror/var/postmirror.sh
}
if test "$1" = "configure"; then
	setup_aptmirror_user
	setup_aptmirror_clean
	set_aptmirror_owner
fi
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