group file operations

#!/usr/bin/perl -w

use strict;
use warnings;

use Encode;

binmode STDOUT, ":utf8";
binmode STDIN, ":utf8";
binmode STDERR, ":utf8";

#use Cwd;
#my $dir = getcwd();

my ($pat, $what, $to, $cmd) = @ARGV;
my $ln = 0;

$to = '"'.$to.'"';

my $myname = $0;
$myname =~ s/\.\///;

if ( !$pat or !$what or !$to or !$cmd )
  {
    my $me = $myname;
    $me =~ s/^.*\///;
    die 'Usage: ' . $me . ' {filename pattern} {what replace} {replace to} {command to exec}' . "\n"
      . 'Hint in {replace to} you can use $fn. It\'l be replaced by number of file. Files sorted by name in alphabetical order' . "\n"
      .'for example: #> '. $me . ' \'*.c\' \'\w\.\' \'e_$fn\.\' cp' . "\n";
  }


my @old = ();
my @new = ();


# opendir(DIR,$dir);
# my @files = readdir(DIR);
# closedir(DIR);

my @files = glob($pat);

foreach my $fname (@files) {
  if ( $fname =~ m/$myname$/ ) { next; }
  $fname =~ s/\s+$//;
  my $nto = eval($to);
  my $nfname = $fname;
  $nfname =~ s/$what/$nto/;
  if ( $fname ne $nfname )
    {
      push( @old, $fname );
      push( @new, $nfname );
    }
  $ln += 1;
}


print "Now we will exec: " . $cmd . " " . $old[0] . " " . $new[0] . "\nIs it OK(yes/no)?\n";
my $answer = <STDIN>;

if ( $answer eq "yes" )
  {
    for (my $i = 0; $i < ($#old + 1); $i++) {
      system($cmd, $old[$i], $new[$i]);
    }
  }
else
  {
    print "[Canceled]\n";
  }