deb-preinst - package pre-installation maintainer script
A package can perform several pre-installation actions via maintainer scripts, by including an executable preinst file in its control archive (i.e. DEBIAN/preinst during package creation).
The script can
be called in the following ways:
Before the package is installed.
new-preinst install old-version new-version
Before removed package is upgraded.
new-preinst upgrade old-version new-version
Before the package is upgraded.
old-preinst abort-upgrade new-version
If postrm fails during upgrade or fails on failed upgrade.