1#!/usr/bin/env 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; 6use IO::Handle; 7 8binmode STDIN; 9binmode STDOUT; 10 11STDOUT->autoflush(1); 12 13my $needed = 1; 14while (1) { 15 my $char; 16 my $bytes = sysread(STDIN, $char, 1); 17 exit 0 if ($bytes == 0); 18 if ($needed) { 19 print "# "; 20 $needed = 0; 21 } 22 print $char; 23 $needed = 1 if ($char eq "\n"); 24} 25