GNU bug report logs - #7715
cp command on Linux

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From: help-debbugs <at> gnu.org (GNU bug Tracking System)
To: Paul Eggert <eggert <at> cs.ucla.edu>
Cc: tracker <at> debbugs.gnu.org
Subject: bug#7715: closed (cp command on Linux )
Date: Thu, 23 Dec 2010 01:45:02 +0000

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Your message dated Wed, 22 Dec 2010 17:50:52 -0800
with message-id <4D12AAFC.2000203 <at> cs.ucla.edu>
and subject line Re: bug#7715: cp command on Linux
has caused the GNU bug report #7715,
regarding cp command on Linux 
to be marked as done.

(If you believe you have received this mail in error, please contact
help-debbugs <at> gnu.org.)


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7715: http://debbugs.gnu.org/cgi/bugreport.cgi?bug=7715
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From: "Hemant Rumde" <Hemant.Rumde <at> us.ing.com>
To: <bug-coreutils <at> gnu.org>
Subject: cp command on Linux 
Date: Wed, 22 Dec 2010 16:07:20 -0500

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Hi 

I do not log any bug for cp command. In our company, we copy huge Cobol
files before processing data. This is to rollback our data files. 
Suppose A1 is my huge file of 60GB and A1.bk is its backup file, before
we process ( change ) data into A1. Then which of our method
would be faster?

1. Method-1 ( A1.bk exists ) 
    $ cp  A1 A1.bk 

2. Method-2  
    $ rm -f A1.bk 
    $ cp A1 A1.bk 

3. Method-3 
    $ cp --remove-destination A1 A1,bk 

This operation is very simple. But our operators tell, in some cases cp
takes longer time. How can we reduce copying time?

Thanks 
Hemant Rumde 
ING US 
Boston US

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From: Paul Eggert <eggert <at> cs.ucla.edu>
To: Hemant Rumde <Hemant.Rumde <at> us.ing.com>
Cc: 7715-done <at> debbugs.gnu.org
Subject: Re: bug#7715: cp command on Linux
Date: Wed, 22 Dec 2010 17:50:52 -0800

On 12/22/2010 01:07 PM, Hemant Rumde wrote:
> Then which of our method would be faster?

Method 3 is probably a tad faster than method 2,
but whether 1 or 3 is faster depends on the
underlying implementation.  If you're seeing
wildly different performance numbers I'd look
there, not at 'cp' itself.

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