How can I redirect the output from one filehandle into another?

Question

I want to set up a pipeline of processes from within Perl (running on Linux), consisting of two parts run at separate times.

Eg:

Start the consumer process:

open( OUT, "| tar xvf - " ) || die "Failed: tar: $!";

then much later start the producer process:

open( IN, "gpg -d $file |" ) || die "Failed: gpg: $!";

but then somehow redirect the output from gpg into the input to tar.

I can do this by building a loop:

while (<IN> ) {
  print OUT;
}

But I would like to know if I can somehow glue the two processes together with redirection.

Answer 1

Add

pipe( IN, OUT );

Before the two open statements. That's it!

If you want to do anything more complicated, I would recommend the IPC::Run CPAN module:

http://search.cpan.org/dist/IPC-Run/

It lets you start processes, tie their input and outputs together, and add logging or redirection at any point in the chain.