remove double extensions in bash

Question

I am familiar with rename but I was curious does rename still apply for removing duplicate extensions??

Say I have a few files named:

picture2.jpg.jpg
picture9.jpg.jpg
picture3.jpg.jpg
picture6.jpg.jpg

How would you remove the the duplicate extension??

End result:

picture2.jpg
picture9.jpg
picture3.jpg
picture6.jpg

sampson-chen · Accepted Answer · 2012-11-23T21:13:01.067

Assuming:

You only want to perform this in the current working directory (non-recursively)
The double extensions have format precisely as .jpg.jpg:

Then the following script will work:

#!/bin/bash

for file in *.jpg.jpg
do
    mv "${file}" "${file%.jpg}"
done

Explanation:

${file%.jpg}: This part is called Parameter Subsitution.
From the same source: "${var%Pattern} Remove from $var the shortest part of $Pattern that matches the back end of $var."
Note that the "pattern" mentioned here is called globbing, which is different from regular expression in important ways.

To use this script:

Create a new file called clean_de.sh in that directory
Set it to executable by chmod +x clean_de.sh
Then run it by ./clean_de.sh

A Note of Warning:

As @gniourf_gniourf have pointed out, use the -n option if your mv supports it.

Otherwise - if you have a.jpg and a.jpg.jpg in the same directory, it will rename a.jpg.jpg to a.jpg and in the process override the already existing a.jpg without warning.

that's exactly what I needed thank you. I would assume is the %\ doing the change? — DᴀʀᴛʜVᴀᴅᴇʀ, Nov 23 '12 at 20:43
If your `mv` has the `-n` option (no clobber option), you can use it, just to be safe in case the target file already exists. — gniourf_gniourf, Nov 23 '12 at 21:09

score 5 · Answer 2 · answered Nov 24 '12 at 08:07

5

One line rename command should also suffice (for your case at least):

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

answered Nov 24 '12 at 08:07

anishsane

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score 1 · Answer 3 · answered Nov 24 '12 at 09:38

Here is a more general, but still easy solution for this problem:

for oldName in `find . -name "*.*.*"`; do newName=`echo $oldName | rev | cut -f2- -d'.' | rev`; mv $oldName $newName; done

Short explanation:
find . -name "*.*.* - this will find only the files with duplicate extensions recursively

echo $oldName | rev | cut -f2- -d'.' | rev - the trick happens here: the rev command do a reverse on the string, so you now you can see, that you want the whole filename from the first dot. (gpj.gpj.fdsa)

mv $oldName $newName - to actually rename the files

Release Notes: since it is a simple one-line script, you can find unhandled cases. Files with an extra dot in the filename, super-deep directory structures, etc.

This will clobber a similar-named non-double-suffix file. If the directory contains image.jpg.php and image.jpg.jpg, the first file will be deleted. — Lucent, May 05 '21 at 17:15

remove double extensions in bash

3 Answers3