If symlinks must be followed, then still the safest is to use modern technology:

use File::Find;
finddepth {
  wanted => sub {
    return if /^\./;
    my $new = lc $_;
    return if $new eq $_ or -e $new;
    rename $_, $new or warn "Cannot rename $File::Find::name to $File:
+:Find::dir/$new: $!";
  },
  follow => 1,
}, $ARGV[0] || ".";
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-- Randal L. Schwartz, Perl hacker
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