One liners are bad enough; but I swear, "shelling-out" to actual Perl scripts from a Perl script is one of the most offensive things I can see in Perl code. All the wasted cycles, dead electrons, PIDs, (oh the horror!) and server fan RPMs that are consumed for no reason ... incidentally in most (but not all) a simple conversion of the called script to a modulino would; then using it as a library rather than a system call would fix all of that. The only exception I've run across is if the called Perl script is specifically being used for sandboxing necessary privilege escallation; in that case, I think it's fine to treat the Perl script as an opaque userland program.