## file pmo3.pl
use strict;
use IPC::Open3;

my $pid = open3(\*WTRFH, \*RDRFH, \*ERRFH, 'perl', 's1.pl');

print WTRFH "YES or NO\n";
close WTRFH;

while (<RDRFH>) {
    print "found this in RDRFH:\t";
    print;
}

while (<ERRFH>) {
    print "found this in ERRFH:\t";
    print;
}

exit;

##  and second file: s1.pl
use strict;

print "this is printed to STDOUT\n";

while (<STDIN>) {
    chomp;
    print "found in STDIN of <s1.pl>: $_\n";
}

warn "this is warned to STDERR\n";

exit;

__OUTPUT__
!perl pmo3.pl
found this in RDRFH:    this is printed to STDOUT
found this in RDRFH:    found in STDIN of <s1.pl>: YES or NO
found this in ERRFH:    this is warned to STDERR
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