Taylor, Andrew (ASPIRE) wrote: > OK, I'm clearly being dense here then. My understanding was that the > "$?" contained the status of the pid returned by waidpid. > > If waitpid returned a pid from some other process (i.e. not one of my > children) that had failed (i.e return status other than 0) then wouldn't > my test abort the script when it wouldn't need to (as the process that > failed wasn't one of my children) before it got to the redo? > > Or have I firmly grasped the wrong end of the stick?
On some systems, waitpid may return something rather than a child pid or -1. This would happen when the wait was interrupted by something other than a child death. Most likely, it would be zero. The return status, $?, is a 16-bit word of three packed values. See `perldoc perlvar` and search for /\$\?/. It should be set to a non-zero value by the child if the child does not terminate successfully. Most UNIX commands do this; most user-written scripts do not. Also, Windows ignores the return value and always returns zero. $? should not change unless a child process died. -- Just my 0.00000002 million dollars worth, Shawn Programming is as much about organization and communication as it is about coding. I like Perl; it's the only language where you can bless your thingy. -- To unsubscribe, e-mail: beginners-unsubscr...@perl.org For additional commands, e-mail: beginners-h...@perl.org http://learn.perl.org/
