in reply to Understanding fork

The code is correct, but confusing with all the 'if not's. See RMGir's reply above for an explanation of what the code does. However, to make it less confusing, here's a fork()ing framework that uses straight ifs that are easier to understand (at least for me):
use strict; if (defined(my $pid=fork()) { if ($pid) { # $pid is not 0, so this is the parent # Let's redirect the user (more extensive code in your example). redirect_user(); } else { # $pid=0, so this is the child my $retval=do_child_code(); exit $retval; } } else { # Oops, fork() returned undef - something is definitely wrong. DieNice("Unable to fork: $!\n"); } sub do_child_code { # Do your time consuming stuff, setting $retval to # a useful number return $retval; }
You could do without the else block calling do_child_code, and have the child just fall through down to the child code, but this way it's a lot easier to understand and maintain.