Bash script to pad file names

Question

What is the best way, using Bash, to rename files in the form:

(foo1, foo2, ..., foo1300, ..., fooN)

With zero-padded file names:

(foo00001, foo00002, ..., foo01300, ..., fooN)

Answer 1

The following will do it:

for i in ((i=1; i<=N; i++)) ; do mv foo$i `printf foo%05d $i` ; done

EDIT: changed to use ((i=1,...)), thanks mweerden!

Answer 2

Here's a quick solution that assumes a fixed length prefix (your "foo") and fixed length padding. If you need more flexibility, maybe this will at least be a helpful starting point.

#!/bin/bash

# some test data
files="foo1
foo2
foo100
foo200
foo9999"

for f in $files; do
    prefix=`echo "$f" | cut -c 1-3`        # chars 1-3 = "foo"
    number=`echo "$f" | cut -c 4-`         # chars 4-end = the number
    printf "%s%04d\n" "$prefix" "$number"
done

Answer 3

In case N is not a priori fixed:

 for f in foo[0-9]*; do mv $f `printf foo%05d ${f#foo}`; done

Answer 4

Pure Bash, no external processes other than 'mv':

for file in foo*; do
  newnumber='00000'${file#foo}      # get number, pack with zeros
  newnumber=${newnumber:(-5)}       # the last five characters
  mv $file foo$newnumber            # rename
done

Answer 5

I had a more complex case, where the file names had a postfix as well as a prefix, and I also needed to perform a subtraction on the number from the filename. So I wanted foo56.png to become foo00000055.png. I hope this helps if you're doing something more complex.

#!/bin/bash
for file in foo[0-9]*.png; do
  # strip the prefix ("foo") off the file name
  postfile=${file#foo}
  # strip the postfix (".png") off the file name
  number=${postfile%.png}
  # subtract 1 from the resulting number
  i=$((number-1))
  # copy to a new name in a new folder
  cp ${file} ../newframes/$(printf foo%08d.png $i)
done