[debbugs-tracker] bug#12365: closed (Incorrect return value of cp with no-clobber option)

[GNU bug Tracking System]

Your message dated Thu, 06 Sep 2012 08:31:53 -0600
with message-id <address@hidden>
and subject line Re: Should cp -n return 0, when DEST exists?
has caused the debbugs.gnu.org bug report #12365,
regarding Incorrect return value of cp with no-clobber option
to be marked as done.

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12365: http://debbugs.gnu.org/cgi/bugreport.cgi?bug=12365
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> --- Begin Message ---
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> Subject: 
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> Incorrect return value of cp with no-clobber option
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> Date: 
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> Thu, 6 Sep 2012 17:27:52 +0530
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> When -n (--no-clobber) option of cp is used and the DEST file exists, then, as
> expected, cp is not able to copy the SOURCE to DEST.
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> However, cp returns 0 in this case.
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> Shouldn't it return 1 to indicate that copy operation could not be completed?
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> In absence of this indication how is one to know that some recovery
> action like re-trying cp with some other DEST name is required?
>
> Regards,
> Anoop
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>
>
> --- End Message ---

--- Begin Message --- Subject: Re: Should cp -n return 0, when DEST exists? Date: Thu, 06 Sep 2012 08:31:53 -0600 User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:15.0) Gecko/20120828 Thunderbird/15.0

tag 12365 wontfix
thanks

On 09/06/2012 04:50 AM, Anoop Sharma wrote:
> When -n option of cp is used and the DEST file exists, then, as
> expected, cp is not able to copy the SOURCE to DEST.
> 
> However, cp returns 0 in this case.

cp -n is not mandated by POSIX, so we are free to do as we wish here.
But looking at history, we added -n for coreutils 7.1 in Feb 2009, and
the mail from that thread includes:
https://lists.gnu.org/archive/html/bug-coreutils/2008-12/msg00159.html

which states we are modeling after FreeBSD.  A quick check on my FreeBSD
8.2 VM shows:

$ echo one > bar
$ echo two > blah
$ cp -n blah bar
$ echo $?
0
$ cat bar
one

that FreeBSD also returns 0 in this case, and I don't want to break
interoperability.  Therefore, I'm going to close this as a WONTFIX,
unless you also get buy-in from the BSD folks.

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-- 
Eric Blake   address@hidden    +1-919-301-3266
Libvirt virtualization library http://libvirt.org

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