prerm is in bison 2:3.0.4.dfsg-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 | #!/bin/sh
set -e
case "$1" in
upgrade|failed-upgrade)
:;
;;
remove|deconfigure)
update-alternatives --remove yacc /usr/bin/bison.yacc
;;
*)
echo "Undocumented call: \"$@\"" >&2
exit 1
;;
esac
|