Padding numbers in filenames

[Chris F.A. Johnson]

On Mon, 26 Feb 2007, William O'Higgins Witteman wrote:

> I have a mess of sequentially numbered files (1.png, 2.png ... 824.png)
> that I'd like to pad the filenames of so that they sort prettily
> (0001.png, 0002.png ... 0824.png).  I thought to use the rename command,
> but I'm not getting the results I need, and Google didn't help.
>
> Here's what I tried with rename:
>
> rename -n "s/(\d)\.png/000$1png/" *
>
> This would only catch the first 9 files, but I no that I had the right
> method.
>
> I can certainly whip up a quick program in Python or Perl (I could
> probably learn enough Ruby in half an hour too, or Lua, or C, or ...
> you get the picture) but I was curious where I was going wrong with
> rename.  Any suggestions?  Thanks.

    There are at least two different versions of rename, and they do
    not take the same syntax.

    A shell script (this is bash/ksh93 specific) is straightforward:

for file in [1-9]*.png
do
   newname=0000$file
   newname=${newname: -8} ## POSIX: newname=${newname#"${newname%????????}"}
   mv "$file" "$newname"
done


-- 
    Chris F.A. Johnson                      <http://cfaj.freeshell.org>
    ===================================================================
    Author:
    Shell Scripting Recipes: A Problem-Solution Approach (2005, Apress)
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