postinst is in automake1.11 1:1.11.6-4.
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 | #!/bin/sh
set -e
ver=1.11
prio=29
update-alternatives --install /usr/bin/automake automake \
	/usr/bin/automake-$ver $prio \
	--slave /usr/bin/aclocal aclocal /usr/bin/aclocal-$ver \
	--slave /usr/share/man/man1/automake.1.gz automake.1.gz \
	/usr/share/man/man1/automake-$ver.1.gz \
	--slave /usr/share/man/man1/aclocal.1.gz aclocal.1.gz \
	/usr/share/man/man1/aclocal-$ver.1.gz
 |