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

Answer 1

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.