For the path of interpreters, using env is more portable, e.g.,

#!/usr/bin/env perl

Some people have /usr/local/bin/perl, others have /usr/bin/perl, but env finds any on the path. (Don't know if that's FHS compliant.) Known drawbacks: If you keep several versions installed and want a specific one, this may not work. Specifically with perl, you can't use the "-w" option; must "use warnings".