Better way to rename files based on multiple patterns

Two answer: using perl rename or using pure bash

As there are some people who dislike perl, I wrote my bash only version

Renaming files by using the rename command.

Introduction

Yes, this is a typical job for rename command which was precisely designed for:

man rename | sed -ne '/example/,/^[^ ]/p'
   For example, to rename all files matching "*.bak" to strip the
   extension, you might say

           rename 's/\.bak$//' *.bak

   To translate uppercase names to lower, you'd use

           rename 'y/A-Z/a-z/' *

More oriented samples

Simply drop all spaces and square brackets:

rename 's/[ \[\]]*//g;' *.ext

Rename all .jpg by numbering from 1:

rename 's/^.*$/sprintf "IMG_%05d.JPG",++$./e' *.jpg

Demo:

touch {a..e}.jpg
ls -ltr
total 0
-rw-r--r-- 1 user user 0 sep  6 16:35 e.jpg
-rw-r--r-- 1 user user 0 sep  6 16:35 d.jpg
-rw-r--r-- 1 user user 0 sep  6 16:35 c.jpg
-rw-r--r-- 1 user user 0 sep  6 16:35 b.jpg
-rw-r--r-- 1 user user 0 sep  6 16:35 a.jpg
rename 's/^.*$/sprintf "IMG_%05d.JPG",++$./e' *.jpg
ls -ltr
total 0
-rw-r--r-- 1 user user 0 sep  6 16:35 IMG_00005.JPG
-rw-r--r-- 1 user user 0 sep  6 16:35 IMG_00004.JPG
-rw-r--r-- 1 user user 0 sep  6 16:35 IMG_00003.JPG
-rw-r--r-- 1 user user 0 sep  6 16:35 IMG_00002.JPG
-rw-r--r-- 1 user user 0 sep  6 16:35 IMG_00001.JPG

Full syntax for matching SO question, in safe way

There is a strong and safe way using rename utility:

As this is perl common tool, we have to use perl syntax:

rename 'my $o=$_;
        s/[ \[\]]+/-/g;
        s/-+/-/g;
        s/^-//g;
        s/-\(\..*\|\)$/$1/g;
        s/(.*[^\d])(|-(\d+))(\.[a-z0-9]{2,6})$/
                my $i=$3;
                $i=0 unless $i;
                sprintf("%s-%d%s", $1, $i+1, $4)
            /eg while
               $o ne $_  &&
               -f $_;
    ' *

Testing rule:

touch '[ www.crap.com ] file.name.ext' 'www.crap.com - file.name.ext'
ls -1
[ www.crap.com ] file.name.ext
www.crap.com - file.name.ext
rename 'my $o=$_; ...
    ...
    ...' *
ls -1
www.crap.com-file.name-1.ext
www.crap.com-file.name.ext

touch '[ www.crap.com ] file.name.ext' 'www.crap.com - file.name.ext'
ls -1
www.crap.com-file.name-1.ext
[ www.crap.com ] file.name.ext
www.crap.com - file.name.ext
www.crap.com-file.name.ext
rename 'my $o=$_; ...
    ...
    ...' *
ls -1
www.crap.com-file.name-1.ext
www.crap.com-file.name-2.ext
www.crap.com-file.name-3.ext
www.crap.com-file.name.ext

… and so on…

… and it’s safe while you don’t use -f flag to rename command: file won’t be overwrited and you will get an error message if something goes wrong.

Renaming files by using bash and so called bashisms:

I prefer doing this by using dedicated utility, but this could even be done by using pure bash (aka without any fork)

There is no use of any other binary than bash (no sed, awk, tr or other):

#!/bin/bash

for file;do
    newname=${file//[ \]\[]/.}
    while [ "$newname" != "${newname#.}" ] ;do
        newname=${newname#.}
      done
    while [ "$newname" != "${newname//[.-][.-]/.}" ] ;do
        newname=${newname//[.-][.-]/-};done
    if [ "$file" != "$newname" ] ;then
        if [ -f $newname ] ;then
            ext=${newname##*.}
            basename=${newname%.$ext}
            partname=${basename%%-[0-9]}
            count=${basename#${partname}-}
            [ "$partname" = "$count" ] && count=0
            while printf -v newname "%s-%d.%s" $partname $[++count] $ext &&
                  [ -f "$newname" ] ;do
              :;done
          fi
        mv  "$file" $newname
      fi
  done

To be run with files as argument, for sample:

/path/to/my/script.sh \[*

• Replacing spaces and square bracket by dot
• Replacing sequences of .-, -., -- or .. by only one -.
• Test if filename don’t differ, there is nothing to do.
• Test if a file exist with newname…
• split filename, counter and extension, for making indexed newname
• loop if a file exist with newname
• Finaly rename the file.