G'day aquercus,

Welcome to the monastery.

I don't have perl running on any MSWin OSes; however, here's how I might have tackled this on a *nix OS. There may be sufficient here for you to adapt it to your OS. I've added some notes after the code as well as a sample run.

Here's the code (pm_test_tail_pipe.pl):

#!/usr/bin/env perl

use strict;
use warnings;
use autodie qw{:all};

my $tail_cmd = 'tail -f ./pm_test_file_to_tail';
my @tail_captures;

print '*** Start reading from $tail_pipe at ', time, "\n";
my $tail_pid = open my $tail_pipe, '-|', $tail_cmd;

{
    local $SIG{INT} = sub {
        kill INT => $tail_pid if kill 0 => $tail_pid;
        waitpid $tail_pid => 0;
    };

    while (<$tail_pipe>) {
        push @tail_captures, $_;
    }
}

print '*** Stop reading from $tail_pipe at ', time, "\n";

# Possibly process data captured, e.g. for demo only
$_ = uc for @tail_captures;

print '*** Captured via $tail_pipe:', "\n";
print for @tail_captures;
[download]

Notes:

• I haven't included the pipe (|) as part of the tail command. Instead, I've used '-|' in the 3-argument form of open and captured the PID of the tail process.
• local $SIG{INT} = ... traps interrupts (Ctrl-C on *nix) to stop tailing without killing the script. This only takes effect within the anonymous block so it only affects the while loop; outside of this block, interrupts act normally, i.e. Ctrl-C will terminate the script.
• perlport may be of use with respect to kill and waitpid.
• perlipc has information on Signals.

Sample run:

$ cat > pm_test_file_to_tail
line 1
line 2
line 3
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$ cat >> pm_test_file_to_tail
line 4
line 5
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$ pm_test_tail_pipe.pl
*** Start reading from $tail_pipe at 1371707519
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line 6
line 7
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^C*** Stop reading from $tail_pipe at 1371707542
*** Captured via $tail_pipe:
LINE 1
LINE 2
LINE 3
LINE 4
LINE 5
LINE 6
LINE 7
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line 8
line 9
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$ cat pm_test_file_to_tail
line 1
line 2
line 3
line 4
line 5
line 6
line 7
line 8
line 9
[download]