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Re: A quick Q: how do I command something in large amount

On Thu, Sep 15, 2011 at 10:07:16AM -0600, Aaron Toponce wrote:
> On Fri, Sep 16, 2011 at 12:03:40AM +0800, lina wrote:
> > mv *.txt  *.pdf
> >
> > can it be done * way?
> >
> > all the *.txt in current directory?
> Yes. Checkout the rename(1) command. It comes from Perl, and can be used
> for exactly that. Or, you could write a simple for-loop:
>     for FILE in *.txt; do mv $FILE.txt $FILE.pdf; done
> You have options.
Just some additional remarks:
a) the for-loop won't work, as "FILE" is expanded to the name including
   the .txt, so if you have a file "a.txt" this loop will execute 
	   mv a.txt.txt a.txt.pdf
   You need instead
     for FILE in *.txt; do mv $FILE `basename $FILE .txt`.pdf; done
   in order to remove the ".txt" from the variable "$FILE"

b) for-loops in bash can be REALLY problematic, as soon as you have
   special characters in your filenames. Like for example spaces or
   new-lines or other control characters... OK, at least new lines are
   luckily very rare, but they can exist.
   So you should try e.g.
     for FILE in *.txt; do mv "$FILE" "`basename \"$FILE\" .txt`".pdf; done
   (this works at least with spaces in the filename...)


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