#!/usr/bin/env perl
# SPDX-License-Identifier: GPL-2.0
# Prefix all lines with "# ", unbuffered. Command being piped in may need
# to have unbuffering forced with "stdbuf -i0 -o0 -e0 $cmd".
use strict;
use IO::Handle;
binmode STDIN;
binmode STDOUT;
STDOUT->autoflush(1);
my $needed = 1;
while (1) {
my $char;
my $bytes = sysread(STDIN, $char, 1);
exit 0 if ($bytes == 0);
if ($needed) {
print "# ";
$needed = 0;
}
print $char;
$needed = 1 if ($char eq "\n");
}