Let's see: ssh does not touch the STDIN, STDOUT, STDERR streams. But it invokes the remote standard shell to handle arguments. So, get rid of the shell parsing.

Perl can read a program from STDIN, it stops reading at EOF or when it finds the magic "__END__" marker on a line. So, feed the remote Perl a program that implements some kind of read-eval-print loop (you may also call that a RPC server, if you wish), then send commands over STDIN, read results back from STDOUT.

Working (stupid) example:

#!/usr/bin/perl -w

use strict;
use IPC::Open2; # or IPC::Open3

my ($in,$out);

$|=1;
my $pid=open2($out,$in,'/usr/bin/ssh','foken@10.50.20.82','/usr/bin/pe
+rl');

print $in <<'__end_of_perl__';
$|=1;
use strict;
use warnings;

print "ok, running with PID $$\n";
while (<STDIN>) {
        chomp;
        print "File $_ has a size of ",-s($_)," bytes\n";
}

# the next line is important:
__END__
__end_of_perl__

print "Loaded\n";
print "Reading boot message: ";
my $info=<$out>;
print $info;

for my $file ('/etc/passwd','/etc/motd','/etc/issue') {
        print "Requesting $file\n";
        print $in "$file\n";
        print "Reading: ";
        $info=<$out>;
        print $info;
}
[download]

Output:

Loaded
Reading boot message: ok, running with PID 13498
Requesting /etc/passwd
Reading: File /etc/passwd has a size of 1468 bytes
Requesting /etc/motd
Reading: File /etc/motd has a size of 20 bytes
Requesting /etc/issue
Reading: File /etc/issue has a size of 24 bytes
[download]

To do:

• replace "foken@10.50.20.82" with the username and hostname of the machine you want to talk with
• replace the remote while-loop with the code you actually want to run
• close the file handles when you are done (optional, but recommended)
• add error checks (optional, but recommended)
• replace the simple-and-stupid line-oriented protocol with some more advanced protocol (optional)
• replace IPC::Open2 with IPC::Open3, open2() with open3(), and look for errors written to the remote STDERR
• Encode data, e.g. using JSON, Data::Dumper, XML, YAML, whatever you like (optional)

Alexander