GNU Stow is a program for running the installation of software packages, preserving them separately (/usr/local/stow/emacs vs. /usr/local/stow/perl, for example) while building them to appear for installing them in the similar place (/usr/local). Stow is a Perl script that must be run accurately under the Perl 4 and Perl 5. You must also install the Perl before running the Stow. Stow was motivated by Carnegie Mellon's Depot program, but is significantly simpler.