Re^2: Effect of redirecting output to /dev/null on $? value

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Re^3: Effect of redirecting output to /dev/null on $? value by hippo (Archbishop) on Aug 03, 2020 at 15:44 UTC
This is pretty much all covered in the docs for system(). Why does adding a redirect to /dev/null increase the complexity enough to invoke the shell? Because it's the shell that does the redirection. 🦛	[reply]
Re^3: Effect of redirecting output to /dev/null on $? value by ikegami (Patriarch) on Aug 03, 2020 at 17:01 UTC
How is the command executed if the shell is not invoked? By asking to system execute the specified program instead of asking the system to execute `/bin/sh`. Why does adding a redirect to /dev/null increase the complexity enough to invoke the shell? There's no point in including an entire shell in Perl. I don't know exactly what part of shell command parsing is implemented in Perl. Finally, what method is used to execute the command if I had instead used perl's system() function instead of the backticks? `system($cmd)`, `exec($cmd)`, `open(my $pipe, '-\|', $cmd)` (and its 2-arg form) and `open(my $pipe, '\|-', $cmd)` (and its 2-arg form) work the same way as `$cmd` (aka qx`$cmd` aka `readpipe($cmd)`). `system($prog, LIST)` where `LIST` returns at least one scalar won't invoke the shell.^[1] `system({ $prog } $prog, LIST)` won't invoke the shell. It can in Windows.	[reply] [d/l] [select]