preinst is in php5-imap 5.3.5-0ubuntu2.
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 | #!/bin/sh
set -e
if [ -L /usr/share/doc/php5-imap ]; then
# We must be upgrading from a version that was previously
# built from the php5 source package
rm -f /usr/share/doc/php5-imap
fi
exit 0
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