postinst is in tilix 1.7.7-1ubuntu2.
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 | #!/bin/sh -e
set -e
if [ "$1" = "configure" ]; then
	update-alternatives --install /usr/bin/x-terminal-emulator \
	x-terminal-emulator /usr/bin/tilix.wrapper 30 \
	--slave /usr/share/man/man1/x-terminal-emulator.1.gz \
	x-terminal-emulator.1.gz /usr/share/man/man1/tilix.1.gz
fi
 |