Batch rename sequential files by padding with zeroes

Python

import os
path = '/path/to/files/'
for filename in os.listdir(path):
    prefix, num = filename[:-4].split('_')
    num = num.zfill(4)
    new_filename = prefix + "_" + num + ".png"
    os.rename(os.path.join(path, filename), os.path.join(path, new_filename))

you could compile a list of valid filenames assuming that all files that start with "output_" and end with ".png" are valid files:

l = [(x, "output" + x[7:-4].zfill(4) + ".png") for x in os.listdir(path) if x.startswith("output_") and x.endswith(".png")]

for oldname, newname in l:
    os.rename(os.path.join(path,oldname), os.path.join(path,newname))

---

Bash

(from: http://www.walkingrandomly.com/?p=2850)

In other words I replace file1.png with file001.png and file20.png with file020.png and so on. Here’s how to do that in bash

#!/bin/bash
num=`expr match "$1" '[^0-9]*\([0-9]\+\).*'`
paddednum=`printf "%03d" $num`
echo ${1/$num/$paddednum}

Save the above to a file called zeropad.sh and then do the following command to make it executable

chmod +x ./zeropad.sh

You can then use the zeropad.sh script as follows

./zeropad.sh frame1.png

which will return the result

frame001.png

All that remains is to use this script to rename all of the .png files in the current directory such that they are zeropadded.

for i in *.png;do mv $i `./zeropad.sh $i`; done

---

Perl

(from: Zero pad rename e.g. Image (2).jpg -> Image (002).jpg)

use strict;
use warnings;
use File::Find;

sub pad_left {
   my $num = shift;

   if ($num < 10) {
      $num = "00$num";
   }
   elsif ($num < 100) {
      $num = "0$num";
   }

   return $num;
}

sub new_name {
   if (/\.jpg$/) {
      my $name = $File::Find::name;
      my $new_name;
      ($new_name = $name) =~ s/^(.+\/[\w ]+\()(\d+)\)/$1 . &pad_left($2) .')'/e;
      rename($name, $new_name);
      print "$name --> $new_name\n";
   }
}

chomp(my $localdir = `pwd`);# invoke the script in the parent-directory of the
                            # image-containing sub-directories

find(\&new_name, $localdir);

---

Rename

Also from above answer:

rename 's/\d+/sprintf("%04d",$&)/e' *.png

Fairly easy, although it combines a few features not immediately obvious:

@echo off
setlocal enableextensions enabledelayedexpansion
rem iterate over all PNG files:
for %%f in (*.png) do (
    rem store file name without extension
    set FileName=%%~nf
    rem strip the "output_"
    set FileName=!FileName:output_=!
    rem Add leading zeroes:
    set FileName=000!FileName!
    rem Trim to only four digits, from the end
    set FileName=!FileName:~-4!
    rem Add "output_" and extension again
    set FileName=output_!FileName!%%~xf
    rem Rename the file
    rename "%%f" "!FileName!"
)

Edit: Misread that you're not after a batch file but any solution in any language. Sorry for that. To make up for it, a PowerShell one-liner:

gci *.png|%{rni $_ ('output_{0:0000}.png' -f +($_.basename-split'_')[1])}

Stick a ?{$_.basename-match'_\d+'} in there if you have other files that do not follow that pattern.