open, ipc, and return codes

[gary]

Hi,

Is there a way to get the return code from the child process that was started with open?

open(STATUS, "mycommand |") || die "can't fork: $!";
while (<STATUS>) {
bla;
}
close STATUS || die "bad mycommand: $! $?";

but what I need is the return code from "mycommand" itself. Is there a way to do this?

thanks,
gary

 

[Steve Grazzini]

Is there a way to get the return code from the child process
that was started with open?

close STATUS || die "bad mycommand: $! $?";

That's not quite right. (Precedence problem.)

close(STATUS) or die "command failed: $! $?";

but what I need is the return code from "mycommand" itself. Is
there a way to do this?

If the exit status is nonzero, close() will return undef and the
wait() status is in $?.

 

[gary]

Excellent. Thanks for the help.

If that example is wrong then the perldoc is wrong! My code was much messier so I lifted the example code directly from the perldoc: http://www.perldoc.com/perl5.6.1/pod/perlipc.html#Using-open()-for-IPC

again, thanks!

gary

 

[Steve Grazzini]

If that example is wrong then the perldoc is wrong!

Hmm.

It's not really wrong as in "broken", but wrong as in "apt to confuse".
It confused me -- the proper rule is: built-in functions that take one
argument have the highest precedence, while other built-ins fall somewhere
in between "||" (relatively high precedence) and "or" (relatively low).

print $text || die $!; # doesn't work
close FH || die $!; # does work

Sorry for the mix-up.