postinst is in asterisk-config 1:1.8.10.1~dfsg-1ubuntu1.
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 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49  | #! /bin/sh
set -e
# summary of how this script can be called:
#        * <postinst> `configure' <most-recently-configured-version>
#        * <old-postinst> `abort-upgrade' <new version>
#        * <conflictor's-postinst> `abort-remove' `in-favour' <package>
#          <new-version>
#        * <deconfigured's-postinst> `abort-deconfigure' `in-favour'
#          <failed-install-package> <version> `removing'
#          <conflicting-package> <version>
case "$1" in
    configure)
	set +e # ignore errors temporarily
	# find conffiles under /etc/asterisk belonging to asterisk-config
	# and chown them to user asterisk.
	dpkg-query -W -f='${Conffiles}\n' asterisk-config 2>/dev/null | \
	  sed -nr -e 's; (/etc/asterisk/.*) [0-9a-f]*;\1;p' | \
	while read conffile; do
		chown asterisk: ${conffile} 2>/dev/null
	done
	# handle them in the end with a glob since it's way faster
	dpkg-statoverride --quiet --list '/etc/asterisk/*' | while read STAT; do
		chown `echo $STAT | cut -d' ' -f 1,2,4 | sed 's/ /:/'` \
			2>/dev/null
	done
	set -e
    ;;
    abort-upgrade|abort-remove|abort-deconfigure)
    ;;
    *)
        echo "postinst called with unknown argument \`$1'" >&2
        exit 1
    ;;
esac
# dh_installdeb will replace this with shell code automatically
# generated by other debhelper scripts.
exit 0
 |