Increment of multiple file prefixes?

Question

I am looking for a way in Bash to rename my file prefixes. These files are all in one folder. No other files will be in it.

00 - Artist - Title.mp3
01 - Artist - Title.mp3

... and so on

to

01 - Artist - Title.mp3
02 - Artist - Title.mp3

... and so on

The prefix can also be only a single (0, 1, 2, ...), double(00, 01, 02, ...), triple, ... prefixes.

Answer 1

Perl solution:

perl -we 'for (@ARGV) {
              my ($n, $r) = /^([0-9]+)(.*)/;
              rename $_, sprintf("%0" . length($n) . "d", 1 + $n) . $r;
          }' *.mp3

The regular expression match extracts the number to $n and the rest to $r. $n + 1 is then formatted by sprintf to be zero padded, having the same length as the original number.

Note that it changes the length of the number for 9, 99, etc.

Answer 2

It's risky business, but it here's a sh solution that seems to work:

ls *.mp3 | sort -rn | while read f
do 
    number=`echo "$f" | sed 's/ .*//'`
    rest=`echo "$f" | sed 's/^[^ ]* //'`

    number2=`expr $number + 1`
    number2f=`printf %02d $number2`

    mv -i "$number $rest" "$number2f $rest"
done

sort -rn so that it won't try to overwrite anything if there are adjacently-numbered files with the same artist and title (which probably won't happen, although it does if I take your example literally).

mv -i so it will ask you before it overwrites anything if there are any of those cases that manage to come up anyway.

If you have a cleaner way you like to break things like $f up into $number and $rest, be my guest.