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From: Dave Angel <davea@davea.name>
Subject: Re:Save to a file, but avoid overwriting an existing file
Date: Wed, 12 Mar 2014 14:22:51 -0400 (EDT)
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Xref: csiph.com comp.lang.python:68290

 zoom <zoom@yahoo.com> Wrote in message:
> Hi!
> 
> I would like to assure that when writing to a file I do not overwrite an 
> existing file, but I'm unsure which is the best way to approach to this 
> problem. As I can see, there are at least two possibilities:
> 
> 1. I could use fd = os.open("x", os.O_WRONLY | os.O_CREAT | os.O_EXCL)
> which will fail - if the file exists. However, I would prefer if the 
> program would try to save under different name in this case, instead of 
> discarding all the calculation done until now - but I' not too well with 
> catching exceptions.
> 

The tempfile module is your best answer,  but if you really need
 to keep the file afterwards,  you'll have the same problem when
 you rename it later. 

I suggest you learn about try/except.  For simple cases it's not
 that tough, though if you want to ask about it, you'll need to
 specify your Python version. 

-- 
DaveA