Renaming multiple files with Perl's ExReg power

Practical command to rename files using regular expressions:

perl -we '$regex = shift(@ARGV); $rep = shift(@ARGV); $rep =~ s/"/\"/g; $rep = qq("$rep"); foreach (@ARGV) { if (/$regex/) { $ren = s/$regex/$rep/geer;  print qq(Renombrando "$_"n          a "$ren"n); rename($_, $ren); }}' <patrón> <reemplazo> <ficheros...>

Brought up regarding the course of Programming Languages in Coursera, whose videos are numbered without prefix zero (“2 – 9 – Functions Formally (856).mp4”), so they are ordered incorrectly in most programs (like VLC).

To fix it in a Linux terminal, first we create an alias for readability (which you can also save permanently in your .bashrc):

alias renamregex='perl -we '''$regex = shift(@ARGV); $rep = shift(@ARGV); $rep =~ s/"/\"/g; $rep = qq("$rep"); foreach (@ARGV) { if (/$regex/) { $ren = s/$regex/$rep/geer;  print qq(Renombrando "$_"n          a "$ren"n); rename($_, $ren); }}''

Then we change to the directory where we have the videos, replacing my directory with yours of course (you can also just press F4 in Dolphin to open a terminal in it, where are you usas?):

cd "~/Documentos/Educación/Cursos en línea/Coursera UoW - Programming Languages/"

And we add an underscore to the duration (so that the name of the video matches the name of the subtitle):

renamregex '(d)(dd).mp4)' '$1_$2' *.mp4

Renombrando "2 - 9 - Functions Formally (856).mp4"
          a "2 - 9 - Functions Formally (8_56).mp4"

Then rename all the files by adding a zero to all the lone digits, except the last one–we don't want to change the extension:

renamregex '(^|D)(d)(D)' '${1}0$2$3' *

Renombrando "2 - 9 - Functions Formally (8_56).mp4"
          a "02 - 09 - Functions Formally (08_56).mp4"

As an extra reward for using the best OS for developers, you can install all the course programs with a single command (for Debian/Ubuntu and friends):

sudo apt-get install emacs24 smlnj sml-mode racket ruby libtcltk-ruby

Although SML mode requires a little fix (to prevent error “require: Constant symbol `:group’ specified in defvar”):

sudo perl -pi -e 's/^(defvar :.*n//' /usr/share/emacs/site-lisp/sml-mode/sml-compat.el
sudo emacs -batch -f batch-byte-compile  /usr/share/emacs2*/site-lisp/sml-mode/sml-compat.el

If you want to use Emacs instead of DrRacket, install Quack y Geyser con:
sudo apt-get install emacs-goodies-el

and for the last Geyser:
wget http://ubuntu.wikimedia.org/ubuntu/pool/universe/g/geiser/geiser_0.4-1_all.deb
sudo dpkg -i geiser_0.4-1_all.deb
rm geiser_0.4-1_all.deb

(You are not of usas ubuntu sausy in the debian Jessie, you can just do apt-get install geiser).

and add to your ~/.emacs:

;; Improved scheme-mode for Racket
(require 'geiser-install)
(require 'quack)
(quack-install)

If you are on Windows, you'll have to install Perl yourself and run something like:

cd "$HOMEMis DocumentosEducaciónCursos en líneaCoursera UoW - Programming Languages" 

perl -we '$regex = shift(@ARGV); $rep = shift(@ARGV); $rep =~ s/"/\"/g; $rep = qq("$rep"); foreach (@ARGV) { if (/$regex/) { $ren = s/$regex/$rep/geer;  print qq(Renombrando "$_"n          a "$ren"n); rename($_, $ren); }}'
'(d)(dd).mp4)' '$1_$2' *.mp4

perl -we '$regex = shift(@ARGV); $rep = shift(@ARGV); $rep =~ s/"/\"/g; $rep = qq("$rep"); foreach (@ARGV) { if (/$regex/) { $ren = s/$regex/$rep/geer;  print qq(Renombrando "$_"n          a "$ren"n); rename($_, $ren); }}' '(^|D)(d)(D)' '${1}0$2$3' *.*

But I haven't tried it.