Batch rename sequential files by padding with zeroes

Question

I have a bunch of files named like so:

output_1.png
output_2.png
...
output_10.png
...
output_120.png

What is the easiest way of renaming t

Answer 1

For mass renaming the only safe solution is mmv—it checks for collisions and allows renaming in chains and cycles, something that is beyond most scripts. Unfortunately, zero padding it ain't too hot at. A flavour:

c:> mmv output_[0-9].png output_000#1.png

Here's one workaround:

c:> type file
mmv
[^0-9][0-9] #1\00#2
[^0-9][0-9][^0-9] #1\00#2#3
[^0-9][0-9][0-9] #1\0#2#3
[^0-9][0-9][0-9][^0-9] #1\0#2#3
c:> mmv