blib

Pragma for testing programs against a package before the package has been installed. Given a directory path, blib starts looking for a blib directory structure in that directory; if it doesn't find one there, it works its way back up five levels. If no path is specified, it starts looking in the current directory.

blib is meant to be used from the command line:

perl -Mblib script [args...] perl -Mblib=dir script [args...]

However, you can also call it from a Perl program:

use blib; use blib 'dir';