macOS CLI truncate filenames

I would like to create an automator workflow and inside a shell script, which would rename files:

123456789.jpg -> 456.jpg
etc.

All the files have the same name lenght and I would like to truncate the names with using only the middle characters (6 of them).

Help appreciated!

Thank you for the idea, but I intentionally posted this in the programming section and not in the applications section.

Basically I would just like to know, which parameters to use with "mv" command. It's not important, what is the position of the characters, I'll add that later. And suffix should be preserved.

for f in "$@"
do
Shortname=${f:3:6}
mv "$f" "$Shortname"
done

but it doesn't really work...

Experience? None .

But so far I managed to put together a shell script, which renames files with exiftool, so I can sort pictures by name and date at the same time (YYYY-MM-DD HH-MM-SS).

Here's the final update:

Your disclaimer was spot on. The first thing I did, was to expect "mv" in an automator process to start in a given folder. Well it starts in home folder, as I later learned. The script worked and it nicely renamed all the files and folders in my /home. Lesson learned.

From here on everthing worked like a charm.

This is the final code.

for f in "$@"
do
FILEBASE=$(basename "$f")
FOLDERBASE=$(dirname "$f")
SHORTNAME=20${FILEBASE:14:2}${FILEBASE:10:2}${FILEBASE:6:2}${FILEBASE:16:3}${FILEBASE:20:2}${FILEBASE:23:2}
NEWNAME=$FOLDERBASE"/"$SHORTNAME
mv "$f" "$NEWNAME".mov
done


The problem with movies files on iPhone is, that they are a headache to organize. Timestamp in EXIF is wrong (don't really know why), only the filename is correct.

Video 10. 02. 13 17 42 11.mov

The problem is, that I have my pictures organized as YYYYMMDD HHMMSS. Therfor I needed this script to match the names of the movies.


This is the final result:

Renaming the images via the EXIF timestamp:


Renaming the movies by truncating the filename to match:


Result:




Took quite so time, but I've learned a lot in the process. Coming from Windows I must say that it is astonishing what an average user can accomplish in terms of modifying the UI to his needs with relatively little effort.


Thanks for all the help!