13.6 Alternate Installation Locations (PREFIX=...)

Speaking of installation locations, the Makefile built by the default invocation of Makefile.PL presumes that the module will be installed in the system-wide Perl directory that all Perl programs can access directly with the built-in @INC path.

However, if you are testing a module, you certainly don't want to install it into the system directories, possibly corrupting a previous version of your module and breaking production programs.

Also, if you're not the system administrator, it's unlikely that you can change those central Perl directories because that would be a great way to insert a trojan horse for privileged users to stumble across.^[11]

^[11] Even if you weren't the system administrator, you'd soon have all the powers of the system administrator.

Luckily, the Makefile contains provisions for considering an alternate installation location for scripts, manpages, and libraries. The easiest way to specify an alternate location is with a PREFIX value as a parameter on the command line:

$ perl Makefile.PL PREFIX=~/Testing
Checking if your kit is complete...
Looks good
Writing Makefile for Island::Plotting::Maps

Although the messages don't indicate anything different, the Makefile will now install scripts to $PREFIX/bin, manpages below $PREFIX/man, and libraries below $PREFIX/lib/site_perl. In this case, you're selected a subdirectory of your home directory called Testing as the value of $PREFIX.

If you were a project librarian, managing code for a team of developers, you might instead say something like:

$ perl Makefile.PL PREFIX=/path/to/shared/area

which then builds the files into a shared area. Of course, you'd need write privileges to such a directory, and the rest of the team would have to add the bin subdirectory to their PATH, the man subdirectory to their MANPATH, and the lib/site_perl directory to their @INC path, as you'll see shortly.