source: vendor/perl/5.8.8/win32/sync_ext.pl

=comment

Synchronize filename cases for extensions.

This script could be used to perform following renaming:
if there exist file, for example, "FiLeNaME.c" and
filename.obj then it renames "filename.obj" to "FiLeNaME.obj".
There is a problem when some compilers (e.g.Borland) generate
such .obj files and then "make" process will not treat them
as dependant and already maked files.

This script takes two arguments - first and second extensions to
synchronize filename cases with.

There may be specified following options:
  --verbose    <== say everything what is going on
  --recurse    <== recurse subdirectories
  --dummy      <== do not perform actual renaming
  --say-subdir
Every such option can be specified with an optional "no" prefix to negate it.

Typically, it is invoked as:
  perl sync_ext.pl c obj --verbose

=cut

use strict;

my ($ext1, $ext2) = map {quotemeta} grep {!/^--/} @ARGV;
my %opts = (
  #defaults
    'verbose' => 0,
    'recurse' => 1,
    'dummy' => 0,
    'say-subdir' => 0,
  #options itself
    (map {/^--([\-_\w]+)=(.*)$/} @ARGV),                            # --opt=smth
    (map {/^no-?(.*)$/i?($1=>0):($_=>1)} map {/^--([\-_\w]+)$/} @ARGV),  # --opt --no-opt --noopt
  );

my $sp = '';
sub xx {
  opendir DIR, '.';
  my @t = readdir DIR;
  my @f = map {/^(.*)\.$ext1$/i} @t;
  my %f = map {lc($_)=>$_} map {/^(.*)\.$ext2$/i} @t;
  for (@f) {
    my $lc = lc($_);
    if (exists $f{$lc} and $f{$lc} ne $_) {
      print STDERR "$sp$f{$lc}.$ext2 <==> $_.$ext1\n" if $opts{verbose};
      if ($opts{dummy}) {
        print STDERR "ren $f{$lc}.$ext2 $_.$ext2\n";
      }
      else {
        system "ren $f{$lc}.$ext2 $_.$ext2";
      }
    }
  }
  if ($opts{recurse}) {
    for (grep {-d&&!/^\.\.?$/} @t) {
      print STDERR "$sp\\$_\n" if $opts{'say-subdir'};
      $sp .= ' ';
      chdir $_ or die;
      xx();
      chdir ".." or die;
      chop $sp;
    }
  }
}

xx();