I apparently don't understand what is going on with pipes here in Unix, please help.

The intent is to create 2 child processes from a perl script. The script writes to one child process, who passes that (via named pipe) to the second child process, who sends the data to stdout. The script then reads the data from child 2 and prints it.

use strict;
use warnings;
use FileHandle;

# Create named pipe...
my $pipe = "/tmp/mypipe";
system("ksh -c 'if [ ! -p $pipe ]; then mkfifo $pipe; fi'");

# Setup input process...
open(IN, '|-', "cat - > $pipe") || die "Can't open IN process: $!";
IN->autoflush(1);

# Setup output process...
open(OUT, '-|', "tail -f $pipe") || die "Can't open OUT process: $!";
OUT->autoflush(1);

# Send input...
my $input = '12345678901234567890123456789012345678901234567890';
print STDERR "Sending input...\n";
print IN $input;

# Read output...
print "Reading...\n";
my $line;
while($line = <OUT>) {
    print $line
}
[download]

Thanks

-Craig