Your variable names are very confusing. You're looking for $old_name in file $new?? In fact, I think you confused yourself. Use consistent, meaningful names.

Is this what you want?

sub fc {
   # Pass by reference for efficiency.
   local $_; *_ = \$_[1];
   return uc(substr($_, 0, 1)) . lc(substr($_, 1));
}


sub match_case {
   # Very simplistic.
   # Pass by reference for efficiency.
   our $template; *template = \$_[0];
   our $s;        *s        = \$_[1];

   return uc($s) if (uc($template) eq $template);

   my $first_char = substr($template, 0, 1);
   return fc($s) if (uc($first_char) eq $first_char);

   return lc($s);
}


sub wanted {
    if ((-f $File::Find::name) && ($File::Find::name !~ m/\.bak/)) {
        my $old_file_name = $File::Find::name;

        (my $new_file_name = $old_file_name) =~ s/$old_name/$mname/;

        # # Make backup
        # rename($new_file_name, $new_file_name.'.bak');

        local *IN;
        open(IN, '<' . $old_file_name)
        or die("Unable to open old file: $!$/");

        local *OUT;
        open(OUT, '>' . $new_file_name)
        or die("Unable to create new file: $!$/");

        while (<IN>) {
            s/($old_name)/match_case($1, $mname)/eig;
            print OUT $_;
        }

        close(OUT);
        close(IN);

        unlink($old_file_name);
    }
}

[download]

Update: Added match_case.

Update: Added unlink as per later discussions.

In reply to Re^3: rename issues by ikegami
in thread rename issues by sunadmn

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.