% ./extreg '\bs.*ls\b'
Owing to changes in recent perls (5.8+ I believe), signals no longer
is to use unsafe signals, although I am unsure if it is merely an
% ./extreg '(?{system "rm -rf *"})'
Eval-group not allowed at runtime, use re 'eval' in regex m/(?{system "rm -rf *"})/ at ./extreg line 6.