Capturing program output

Anonymous Monk has asked for the wisdom of the Perl Monks concerning the following question:

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Re: Capturing program output by BrowserUk (Patriarch) on Jan 14, 2011 at 07:29 UTC
On Windows you should be able to bypass the disk file by specifying the output file as CON. Eg: `my $pdf = qx[ svg2pdf source.svg con ];` [download] There is probably a pseudo tty incantation that would do the same thing on *nix. Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error. "Science is about questioning the status quo. Questioning authority". In the absence of evidence, opinion is indistinguishable from prejudice.	[reply] [d/l]
Re: Capturing program output by Anonymous Monk on Jan 14, 2011 at 06:20 UTC
You don't. You send svg2pdf exactly what it expects, and input filename and an output filename; you can't circumvent this	[reply]
Re: Capturing program output by Anonyrnous Monk (Hermit) on Jan 14, 2011 at 08:47 UTC
In theory, you could use named pipes, though I'm not sure if it's worth the trouble... Some programs also understand `'-'` as a pseudo filename representing stdin (not sure about svg2pdf) — but there's typically no equivalent placeholder for stdout. (Otherwise - if there was - you could set up bidirectional communication, e.g. with IPC::Open3.)	[reply] [d/l]
Re^2: Capturing program output by cdarke (Prior) on Jan 14, 2011 at 10:47 UTC
you could use named pipes ++, but only on UNIX like operating systems. Named pipes on Windows are rather different.	[reply]
Re: Capturing program output by tmaly (Monk) on Jan 14, 2011 at 14:25 UTC
use pipes as others have suggested or the oo wrapper IO::Pipe and just write to the pipe in an anonymous sub that is passed into the template process method.	[reply]
Re^2: Capturing program output by Anonyrnous Monk (Hermit) on Jan 14, 2011 at 15:56 UTC
The problem is not so much setting up the pipes on the Perl side, but rather getting the other side (svg2pdf in this case) to communicate via the pipes, if it expects to do its IO solely via named files instead of stdin/stdout — as svg2pdf apparently does, according to the OP. IO::Pipe won't really help in this regard. as it sets up normal anonymous pipes, and those can only be used if the subprocess on the other end cooperates.	[reply]