Example 12-5. examples/shell/change_files.pl

#!/usr/bin/perl
use strict;
use warnings;

use File::Find qw(find);

my $dir = ".";
if (defined $ARGV[0]) {
    $dir = $ARGV[0];
}


find( \&change_file, $dir);
 

sub change_file {
    if (not -f $_) {
        return;
    }
    if (substr($_, -3) ne ".pl") {
        return;
    }
    print "$_\n";
    my $data;
    if (open my $fh, "<", $_) {
        local $/ = undef;
        $data = <$fh>;
    } else {
        warn "Could not open '$_' for reading\n";
        return;
    }

    $data =~ s/Copyright Old/Coyright New/g;
    # Let's not ruin our example files....
    my $new_name = "$_.new";

    if (open my $fh, ">", $new_name) {
        print $fh $data;
    } else {
        warn "Could not open '$new_name' for writing\n";
    }
    return;
}