It's said, that

The open2() and open3() functions are unlikely to work anywhere except on a Unix system, or at least one purporting POSIX compliance.

There are, however, examples of the opposite, i.e. open2 can work on Windows.

I want my Perl script to dynamically create Postscript code, invoke the Ghostscript, feed it, collect the output for further tasks. Without any IPC:

use strict;
use warnings;

my $in_fn  = 'in.ps';
my $out_fn = 'out.pdf';
open my $fh, '>', $in_fn;
print $fh <<'END';
%!PS
%
% skipped
%
showpage
END
close $fh;

system 'gswin32c', '-q', '-sDEVICE=pdfwrite', '-o', $out_fn, $in_fn;

# now do something useful with out.pdf
[download]

Ghostscript can use pipes, therefore I thought about more efficient implementation. Below, for simplicity, GS doesn't produce any output except error messages. E.g., using IPC::Run3:

use strict;
use warnings;
use IPC::Run3;

run3 [
    'gswin32c',
    '-q',
    '-sDEVICE=nullpage',
    '-'
    ],
    \ 'syntax error!',
    \ my $out,
    \ my $err,
    {
        binmode_stdin  => 1,
        binmode_stdout => 1,
    };
print "*** STDOUT ***\n$out\n";
print "*** STDERR ***\n$err\n";
[download]

It works, but module's documentation says about nearly always creating temporary files. Therefore it's all nothing but syntactic sugar compared to no-IPC solution above.

The IPC::Open2, however, won't work, it just hangs indefinitely (and so does GS process):

use strict;
use warnings;
use IPC::Open2;

my ( $in, $out, );
my $pid = open2 $out, $in, 'gswin32c -q -sDEVICE=nullpage -';
$in-> autoflush( 1 );
print $in "syntax error!\n\cZ\n";
close $in;
print do { local $/; <$out> };
close $out;
waitpid( $pid, 0 );
[download]

Autoflushing, and ctrl-Z were my futile attempts to make it work.

I understand, efficiency gain of in-memory buffers vs disk-IO can be negligible. But, if not for this case, but for the future -- are there clear advice about when IPC::Open\d will work on Windows, and when not to waste time trying?

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