File Content: prefix.pl #!/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"); } Submit