Perl in a Nutshell, 2nd Edition

IPC::Open3

IPC::Open3 works like IPC::Open2.

use IPC::Open3;

$pid = open3($wtr, $rdr, $err, $cmd_with_args);
$pid = open3($wtr, $rdr, $err, $cmd, "arg1", "arg2", ...);

The following differences apply:

• The first two arguments ($ wtr and $ rdr) are passed in the opposite order.

• A third filehandle can be passed, for standard error. If this argument is given as “”, then STDERR and STDOUT for $cmd are on the same filehandle.

• If $wtr begins with <, then the leading < is stripped from the name, and the remainder is assumed to be a regular filehandle for an open file, rather than a reference to a typeglob. open3 opens this file as STDIN for $cmd and closes it in the parent. Likewise, if $rdr or $err begins with >, then $cmd directs STDOUT or STDERR directly to that file rather than to the parent.