1#!/usr/bin/perl
2# SPDX-License-Identifier: GPL-2.0
3# Prefix all lines with "# ", unbuffered. Command being piped in may need
4# to have unbuffering forced with "stdbuf -i0 -o0 -e0 $cmd".
5use strict;
6
7binmode STDIN;
8binmode STDOUT;
9
10STDOUT->autoflush(1);
11
12my $needed = 1;
13while (1) {
14	my $char;
15	my $bytes = sysread(STDIN, $char, 1);
16	exit 0 if ($bytes == 0);
17	if ($needed) {
18		print "# ";
19		$needed = 0;
20	}
21	print $char;
22	$needed = 1 if ($char eq "\n");
23}
24