NAME

IO::CaptureOutput - capture STDOUT and STDERR from Perl code, subprocesses or XS

VERSION

This documentation describes version 1.04_01.

SYNOPSIS

    use IO::CaptureOutput qw(capture capture_exec qxx);

    my ($stdout, $stderr);
    capture sub {noisy(@args)}, \$stdout, \$stderr;
    sub noisy {
        my @args = @_;
        warn "this sub prints to stdout and stderr!";
        ...
        print "finished";
    }

    ($stdout, $stderr) = capture_exec( 'perl', '-e', 
        'print "Hello "; print STDERR "World!"');

DESCRIPTION

This module provides routines for capturing STDOUT and STDERR from forked system calls (e.g. system(), fork()) and from XS/C modules.

FUNCTIONS

The following functions are be exported on demand.

capture(\&subroutine, \$output, \$error)

Captures everything printed to STDOUT and STDERR for the duration of &subroutine. $output and $error are optional scalar references that will contain STDOUT and STDERR respectively.

Returns the return value(s) of &subroutine. The sub is called in the same context as capture() was called e.g.:

@rv = capture(sub {wantarray}); # returns true
$rv = capture(sub {wantarray}); # returns defined, but not true
capture(sub {wantarray});       # void, returns undef

capture() is able to trap output from subprocesses and C code, which traditional tie() methods are unable to capture.

Note: capture() will only capture output that has been written or flushed to the filehandle.

capture_exec(@args)

Captures and returns the output from system(@args). In scalar context, capture_exec() will return what was printed to STDOUT. In list context, it returns what was printed to STDOUT and STDERR

    my $output = capture_exec('perl', '-e', 'print "hello world"');

    my ($output, $error) = capture_exec('perl', '-e', 'warn "Test"');

capture_exec passes its arguments to CORE::system it can take advantage of the shell quoting, which makes it a handy and slightly more portable alternative to backticks, piped open() and IPC::Open3.

You can check the exit status of the system() call with the $? variable. See perlvar for more information.

qxx(@args)

This is an alias of capture_exec

SEE ALSO

• IPC::Open3

• IO::Capture

• IO::Utils

AUTHORS

• Simon Flack <simonflk _AT_ cpan.org> (original author)

• David Golden <dagolden _AT_ cpan.org> (co-maintainer since version 1.04)

COPYRIGHT AND LICENSE

Portions copyright 2004, 2005 Simon Flack. Portions copyright 2007 David Golden. All rights reserved.

You may distribute under the terms of either the GNU General Public License or the Artistic License, as specified in the Perl README file.