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Switch the placement of 2 strings in filename, for all files in the folder with bash

November 18, 2021

I made a mistake when scraping data, and now my files get allways sorted in the wrong order.
Order in the filename now is DD:MM:YYYY but i need it to be MM:DD:YYYY

Examples of the filenames:

07.08.2020-Cf_J-rraZD4.webm      
15.02.2020-KigC0ER_On4.webm      
22.09.2020-m3iAo8SYBko.webm.srt  
30.07.2020-8Qy94fGod_0.webm.srt
07.08.2020-Cf_J-rraZD4.webm.srt  
15.02.2020-KigC0ER_On4.webm.srt

Is there a simple way to do this with bash?

>Solution :

Use parameter expansion with the ${var:offset:length} syntax to extract parts of the filenames.

#! /bin/bash
for f in * ; do
    new=${f:3:3}${f:0:2}${f:5}
    if [[ -f $new ]] ; then
        echo "Can't rename $f: $new already exists!" >&2
    else
        mv "$f" "$new"
    fi
done

To just generate the new names, you can process the list of old names with sed:

sed 's/^\(..\)\.\(..\)/\2.\1/'

^ matches the start of a string
$..$ captures two characters, the first such group can be referenced as \1, the second one as \2.
\. matches a literal dot.