Perl/Useful hacks

Rename the contents of directory

• How to rename everything that ends with ".old " to the same name with ".new". Here's how to do it in Perl nicely:

foreach my $file (glob "*.old") {
  my $newfile = $file;
  $newfile =~ s/\.old$/.new/;
  if (-e $newfile) {
    warn "can't rename $file to $newfile: $newfile exists\n";
  } elsif (rename $file, $newfile) {
    ## success, do nothing
  } else {
    warn "rename $file to $newfile failed: $!\n";
  }
}

Thought there is much faster way to do this in bash i bet (link from here if you know of one)