# File renaming question

**URL:** <https://www.ruby-forum.com/t/file-renaming-question/91709>\
**Category:** Ruby\
**Created:** [April 11, 2007, 7:48pm UTC](https://www.ruby-forum.com/t/file-renaming-question/91709 "2007-04-11T19:48:56Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![bodikp](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/b/e79b87/32.png) [@bodikp](https://www.ruby-forum.com/u/bodikp)\
**Post date:** [April 11, 2007, 7:48pm UTC](https://www.ruby-forum.com/t/file-renaming-question/91709/1 "2007-04-11T19:48:56Z")

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Hi,  
I just want to do a simple case-changing operation, if needed. The file  
renaming scheme below works for me, but, if any files in my directory  
are already lowercase, then, the script fails. How can I accommodate  
files that may or may not be lowercase to begin with and just make them  
lowercase, whatever they originally were. It seems to me that the “!” is  
what’s demanding that my original files here be upper-case, but, I can’t  
seem to get the thing to work without that “!.”

Thanks,  
Peter

require ‘FileUtils’

Dir.chdir(“C:/bitmaps/notif”)

Dir.glob("\*.pdf").each do |file|  
File.rename("#{file}", “#{file.downcase!}”)  
FileUtils.mv(file, “c:/bitmaps/notif/scratch”)  
end  
…

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<div class="post-metadata">

**Author:** ![bodikp](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/b/e79b87/32.png) [@bodikp](https://www.ruby-forum.com/u/bodikp)\
**Post date:** [April 11, 2007, 8:29pm UTC](https://www.ruby-forum.com/t/file-renaming-question/91709/2 "2007-04-11T20:29:32Z")

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Alle mercoledì 11 aprile 2007, Peter B. ha scritto:

> Peter  
> …  
> You’re right, what is making your program fail is the !. The problem is  
> that  
> String#downcase! returns nil when the string is already downcase, so the  
> call  
> to rename becomes:

File.rename("#{file}", “”)

(nil.to\_s returns an empty string), and obviously fails. So here, you  
need to  
use downcase, which always returns the string with all characters  
downcased.  
You don’t specify what doesn’t work when you use downcase instead of  
downcase!, but looking at your code, I think that it fails on the call  
to mv.  
If I’m right, the reason is that downcase doesn’t alter its receiver (in  
this  
case, file), so, when you pass file to FileUtils.mv, it still contains  
the  
upcase string. But, at that point, the file with the upcase name doesn’t  
exist anymore and the method fails. Using downcase!, instead, file is  
modified (downcased), so the first parameter to mv is the downcase  
string,  
which corresponds to an existing file. To solve your problem, you can  
substitute downcase! with downcase in the call to rename and file with  
file.downcase in the call to mv.

I hope this helps

Stefano

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<div class="post-metadata">

**Author:** ![bodikp](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/b/e79b87/32.png) [@bodikp](https://www.ruby-forum.com/u/bodikp)\
**Post date:** [April 11, 2007, 8:37pm UTC](https://www.ruby-forum.com/t/file-renaming-question/91709/3 "2007-04-11T20:37:26Z")

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Stefano C. wrote:

To solve your problem, you can

> substitute downcase! with downcase in the call to rename and file with  
> file.downcase in the call to mv.
> 
> I hope this helps
> 
> Stefano

Brilliant. Yes, that did it. I got rid of the screamer, !, and I put in  
file.downcase with my move command. Thank you very much!