Assuming your OS is some *nix flavor, the following might do what you need with a little help from sed: 
#!/usr/bin/perl

use strict;
use warnings;

open my $cmd, "-|", "(SHELL_COMMAND | sed 's/^/stdout:/') 2>&1";

my $stdout;
my $stderr;

while( <$cmd> ) {
  if( s/^stdout:// ) {
     $stdout .= $_;
  } else {
     $stderr .= $_;
  }
}
close $cmd;

print "This is stdout:\n$stdout";
print "This is stderr:\n$stderr";

[download]
It assumes that nothing printed to stderr begins with stdout:. If it does, choose a different string to use.

-John

In reply to Re: Easy way to capture STDOUT and STDERR without IPC by johna
in thread Easy way to capture STDOUT and STDERR without IPC by rastoboy

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