Yanick Champoux <yanick.champ...@gmail.com> wrote: > And just to keep things interesting, I've noticed that I forgot the > ending semi-colon that is in the test. But surely that won't-- > > $ perl -E'say system "exit 1"; say system "exit 1;"' > -1 > 256 > > --make a difference...
Ah, I can explain what's going on there. If you give Perl `system` a single argument, it looks at the contents of that string, and decides whether it's a "trivial" command. Trivial commands in this sense are, roughly, those that contain no awkward punctuation characters — which would imply that the command needs to be executed by a shell. If Perl thinks no shell is needed, it optimises by executing the command directly, saving a shell process. Otherwise, it passes the command to the appropriate shell as desired. In this case, if you do `system "exit 1;"`, the semicolon forces `system` to pass the command to a shell, and everything works as expected. On the other hand, `system "exit 1"` with no semicolon is executed directly. But there's no command named `exit` — it's a shell builtin (and has to be). So `system` is giving you the behaviour you get in the "command not found" case, namely a negative return value. -- Aaron Crane ** http://aaroncrane.co.uk/
