tools/testing/selftests/kselftest/prefix.pl

   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".
   5 use strict;
   6 use IO::Handle;
   7
   8 binmode STDIN;
   9 binmode STDOUT;
  10
  11 STDOUT->autoflush(1);
  12
  13 my $needed = 1;
  14 while (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 }