Hello Rina

The following code uses File::Find and Tie::File. Note that Tie::File reads each line into an array so you can attempt a substitution. It also edits the file in place so that the original file will be changed to one with the substitutions. Be *careful* of this code as it will change your original files! Maybe set up a dummy directory with some dummy files to test it. I did to test this script! Note that this will change all files in the top directory, /some/dir_name, and goes through each sub_directory looking at all the files.

#!/usr/bin/perl
use strict;
use warnings;
use Tie::File;
use File::Find;

my @directories_to_search = ("/some/dir_name");
find(\&wanted, @directories_to_search);

sub wanted {
    if (-f) {
        tie my @array, 'Tie::File', $_ or die $!;
        s/\$Log/\$History/gi for @array;
    }
}
[download]

Hope this helps

Chris