You may open a file handle to "in memory" files (ie, scalars... or strings), if you're using a new enough version of Perl. I believe this feature was introduced with 5.8.0.

Per perlfunc:open; 'File handles can be opened to "in memory" files held in Perl scalars via:

open( $fh, '>', \$variable) || die ....
[download]

Though if you try to re-open STDOUT or STDERR as an "in memory" file, you have to close it first.'

Another example provided in the POD is:

open(MEMORY, '>', \$var)
    or die "Can't open memory file: $!\n";
print MEMORY "foo!\n";
[download]