====== BASH - Files - Rename multiple files ======

The **rename** command which is part of the Perl installation helps.

All you need to know is the basics of regular expressions to define how the renaming should happen.

----

To add a '.old' to every file in your current directory.  At the end of each expression ($) a '.old' will be set:

<code bash>
rename 's/$/.old' *
</code>

----

To make the filenames lowercase:

<code bash>
rename 'tr/A-Z/a-z/' *
</code>

----

To remove all double characters:

<code bash>
rename 'tr/a-zA-Z//s' *
</code>

----

You have many JPEG files that look like “img0000154.jpg” but you want the first five zeros removed as you don’t need them:

<code bash>
rename 's/img00000/img/' *.jpg
</code>


<WRAP info>
**NOTE:**  Any Perl operator can be used as an argument.

The actual documentation for the 's' and 'y'/'tr' operators are found in the 'perlop' manpage.

</WRAP>

----

===== Add an extension =====

<code bash>
ls
file1 file2 file3
</code>

Add the extension ".txt"

<code bash>
for F in $(ls);do mv $F $F.txt;done
</code>

Check the result:

<code bash>
ls
file1.rm file2.rm file3.rm
</code>

----

===== Change the extension =====

Change the extension from ".txt" to ".mp3":

<code bash>
for F in $(ls);do mv $F $(echo $F|sed -e 's,\.rm,,').mp3 ;done
</code>

Check the result:

<code bash>
ls
file1.mp3 file2.mp3 file3.mp3
</code>

----

===== Remove the extension =====

<code bash>
for F in $(ls);do mv $F $(echo $F|sed -e 's,\.mp3,,') ;done
</code>

Check the result:

<code bash>
ls
file1 file2 file3
</code>

----

===== Only use ASCII characters =====

<code bash>
find . -type f -exec bash -c 'for f do d=${f%/*} b=${f##*/} nb=${b//[^A-Za-z0-9._-]/_}; [[ $b = "$nb" ]] || mv "$f" "$d/$nb"; done' _ {} +
</code>

<WRAP info>
**NOTE:**  To test, use

<code bash>
find . -type d -exec bash -c 'for f do d=${f%/*} b=${f##*/} nb=${b//[^A-Za-z0-9._-]/_}; [[ $b = "$nb" ]] || echo mv "$f" "$d/$nb"; done' _ {} +
</code>

  * NOTE the **echo** statement included, which just prints out the command that will be run.
    * To actually do the move action, just remove the **echo** part.

</WRAP>


<WRAP info>
**NOTE:**  For directories use

<code bash>
find . -type d -exec bash -c 'for f do d=${f%/*} b=${f##*/} nb=${b//[^A-Za-z0-9._-]/_}; [[ $b = "$nb" ]] || mv "$f" "$d/$nb"; done' _ {} +
</code>

</WRAP>