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
   7 binmode STDIN;
   8 binmode STDOUT;
   9
  10 STDOUT->autoflush(1);
  11
  12 my $needed = 1;
  13 while (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 }