Move numbers in a filename to the start

Question

I have several files in a folder, with names in the form: SOMETEXT1 number SOMETEXT2.mp3, or SOMETEXT number.mp3. I want to rename these to number SOMETEXT SOMETEXT2.mp3, or number SOMETEXT.mp3. Using bash and common GNU command line tools, how would I achieve this?

Answer 1

Using perl-rename (sometimes called prename):

prename -v 's/^(.+) (\d+)( .+|\.[^.]+)$/\2 \1\3/' *

Use -n to just test without renaming.

The same with bash:

re='^(.+) ([0-9]+)( .+|\.[^.]+)$'
for file in *; do
    new=$file
    if [[ "$file" =~ $re ]]; then
        new="${BASH_REMATCH[2]} ${BASH_REMATCH[1]}${BASH_REMATCH[3]}"
    fi
    if [[ "$new" != "$file" ]]; then
        mv -v "$file" "$new"
    fi
done