Sequentially numbering of files in different folders while keeping the name after the number - bash

Question

I have a lot of ogg or wave files in different folders that I want to sequentially number while keeping everything that stands behind the prefixed number. The input may look like this
Folder1/01 Insbruck.ogg
02 From Milan to Rome.ogg
03 From Rome to Naples.ogg
Folder2/01 From Naples to Palermo.ogg
02 From Palermo to Syracrus.ogg
03 From Syracrus to Tropea
The output should be:
Folder1/01 Insbruck.ogg
02 From Milan to Rome.ogg
03 From Rome to Naples.ogg
Folder2/04 From Naples to Palermo.ogg
05 From Palermo to Syracrus.ogg
06 From Syracrus to Tropea.ogg
The sequential numbering across folders can be done with this BASH script that I found here:
find . | (i=0; while read f; do
let i+=1; mv "$f" "${f%/*}/$(printf %04d "$i").${f##*.}";
done)
But this script removes the title that I would like to keep.

Answer 1

TL;DR
Like this, using find and perl rename:
rename -n 's#/\d+#sprintf "/%0.2d", ++$::c#e' Folder*/*
Drop -n switch if the output looks good.
With -n, you only see the files that will really be renamed, so only 3 files from Folder2.
Going further
The variable $::c (or $main::c is a package variable) is a little hack to avoid the use of more complex expressions:
rename -n 's#/\d+#sprintf "/%0.2d", ++our $c#e' Folder*/*
or
rename -n '{ no strict; s#/\d+#sprintf "/%0.2d", ++$c#e; }' Folder*/*
or
rename -n '
do {
use 5.012;
state $c = 0;
s#/\d+#sprintf "/%0.2d", ++$c#e
}
' Folder*/*
Thanks go|dfish & Grinnz on freenode

Answer 2

A bash script for this job would be:
#!/bin/bash
argc=$#
width=${#argc}
n=0
for src; do
base=$(basename "$src")
dir=$(dirname "$src")
if ! [[ $base =~ ^[0-9]+\ .*\.(ogg|wav)$ ]]; then
echo "$src: Unexpected file name. Skipping..." >&2
continue
fi
printf -v dest "$dir/%0${width}d ${base#* }" $((++n))
echo "moving '$src' to '$dest'"
# mv -n "$src" "$dest"
done
and could be run as
./renum Folder*/*
assuming the script is saved as renum. It will just print out source and destination file names. To do actual moving, you should drop the # at the beginning of the line # mv -n "$src" "$dest" after making sure it will work as expected. Note that the mv command will not overwrite an existing file due to the -n option. This may or may not be desirable. The script will print out a warning message and skip unexpected file names, that is, the file names not fitting the pattern specified in the question.

Answer 3

The sequential numbering across folders can be done with this BASH script that I found here:
find . | (i=0; while read f; do
let i+=1; mv "$f" "${f%/*}/$(printf %04d "$i").${f##*.}";
done)
But this script removes the title that I would like to keep.
Not as robust as the accepted answer but this is the improved version of your script and just in case rename is not available.
#!/usr/bin/env bash
[[ -n $1 ]] || {
printf >&2 'Needs a directory as an argument!\n'
exit 1
}
n=1
directory=("$#")
while IFS= read -r files; do
if [[ $files =~ ^(.+)?\/([[:digit:]]+[^[:blank:]]+)(.+)$ ]]; then
printf -v int '%02d' "$((n++))"
[[ -e "${BASH_REMATCH[1]}/$int${BASH_REMATCH[3]}" ]] && {
printf '%s is already in sequential order, skipping!\n' "$files"
continue
}
echo mv -v "$files" "${BASH_REMATCH[1]}/$int${BASH_REMATCH[3]}"
fi
done < <(find "${directory[#]}" -type f | sort )
Now run the script with the directory in question as the argument.
./myscript Folder*/
or
./myscript Folder1/
or
./myscript Folder2/
or a . the . is the current directory.
./myscript .
and so on...
Remove the echo if you're satisfied with the output.