#! /usr/bin/perl
 
##
## Renames files in a directory. If no directory is
## specified, the current directory is used.
##
 
use strict;
use warnings;
use File::Copy;
use Getopt::Long;
 
my $directory = "";
my $from      = "";
my $to        = "";
 
my $getOptionsResult=GetOptions(
    "--directory=s" => \$directory,
    "--from=s"      => \$from,
    "--to=s"        => \$to,
    );
 
 
&displayUsageAndDie if $to eq "";
&displayUsageAndDie if $from eq "";
$directory = "." if $directory eq "";
 
 
opendir(my $dh,$directory) or die "Unable to open $directory: $!";
while(readdir($dh))
{
    &renameFiles($_,$to) if m/$from/;
}
close($dh);
 
 
sub renameFiles()
{
    my $f = $_;
    chomp $f;
    (my $t = $f) =~ s/$from/$to/g;
    printf("renaming '%s' to '%s'\n",$f,$t);
    move($f, $t) or die(qq{failed to move $f -> $t});
}
 
 
sub displayUsageAndDie()
{
    print "
Renames files in a directory. If no directory is
specified, the current directory is used.
 
usage:
    rename --from from --to to [--directory directory]
 
";
    exit 1;
}