$ perl -v | head -2 | tail -1 This is perl 5, version 18, subversion 0 (v5.18.0) built for darwin-thread-multi-2level $ perl -e 'use 5.020; no 5.024' Perl v5.20.0 required--this is only v5.18.0, stopped at -e line 1. BEGIN failed--compilation aborted at -e line 1. $ #### $ perl -v | head -2 | tail -1 This is perl 5, version 24, subversion 0 (v5.24.0) built for darwin-thread-multi-2level $ perl -e 'use 5.020; no 5.024' Perls since v5.24.0 too modern--this is v5.24.0, stopped at -e line 1. BEGIN failed--compilation aborted at -e line 1. $ #### $ perl -v | head -2 | tail -1 This is perl 5, version 22, subversion 0 (v5.22.0) built for darwin-thread-multi-2level $ perl -e 'use 5.020; no 5.024' $