Ubuntu – How to rename all files in folder with name ending with “_backup”

Assuming you want to follow the shell globbing order while sorting files, you can do:

#!/bin/bash
counter=0
for file in *; do 
    [[ -f $file ]] && echo mv -i "$file" $((counter+1)).png && ((counter++))
done

Here looping over all the files in the current directory and renaming sequentially based on order, if you want to deal with only the .png files, use for file in *.png instead. counter variable will keep track of the increments.

This is a dry-run, remove echo to let the actual renaming action take place.

Example:

$ counter=0; for file in *; do [[ -f $file ]] && echo mv -i "$file" $((counter+1)).png && ((counter++)); done
mv -i file.txt 1.png
mv -i foo.sh 2.png
mv -i bar.txt 3.png

Using find and rename:

find . -iname '-*' -execdir rename -n 's:./-:./:' {} +

find . -iname '-*' matches all filenames beginning with a -, and then -execdir ... {} + runs the command with those filenames as arguments, after cding to the directory containing the files. This means that the command arguments always has filenames of the form ./-foo. Then it's easy to just match the - after the ./ in a regex.