Perl 5.8 has the ability to open strings (scalars) as files, but that feature does not work for capturing output of other programs -- use the backtick method above for that.

If you want to capture the output of a subroutine or module inside your own Perl code, the string file technique works well. I'm including it here because this node is likely to turn up in a search.

use strict;
use PerlIO::scalar;

my $output;
my $file;

if (open($file, ">", \$output)) {
    print $file "This is a test.\n";
    close($file);
    print $output;
}
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If you want to redirect STDOUT to a scalar, close it first and then open it connected to the string scalar. You will get an error if you try to do anything that requires a "real" file. (Calling system(...) will fail for example.)