Bash script to pad file names

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)

From stackoverflow Troyzor

• 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!

  mweerden : Instead of using seq I would suggest writing for ((i=1; i<=N; i++)); do etc. Besides being part of bash, this also avoids having to first generate all numbers and then executing the for.
  From dF

• 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
  

  From amrox

• In case N is not a priori fixed:

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

  From Chris Conway

• 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
  

  From fgm

• 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
  

  From Michael Baltaks