GNU bug report logs - #7365
stat bug: %Z appends .000000000

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Message #5 received at submit <at> debbugs.gnu.org (full text, mbox):

From: IgnorantGuru <ignorantguru <at> users.sourceforge.net>
To: bug-coreutils <at> gnu.org
Cc: IgnorantGuru <ignorantguru <at> users.sourceforge.net>
Subject: stat bug: %Z appends .000000000
Date: Wed, 10 Nov 2010 07:59:13 -0700

$ stat -c %Z examplefile 
1289397609.000000000

stat (GNU coreutils) 8.6 installed from Arch Linux repos, executing in a bash shell.

This behavior changed recently - didn't used to have the .000000000 which breaks scripts that use stat.  eg
line 297: ((: 1289301692.000000000: syntax error: invalid arithmetic operator (error token is ".000000000")

Message #8 received at 7365 <at> debbugs.gnu.org (full text, mbox):

From: Eric Blake <eblake <at> redhat.com>
To: IgnorantGuru <ignorantguru <at> users.sourceforge.net>
Cc: 7365 <at> debbugs.gnu.org
Subject: Re: bug#7365: stat bug: %Z appends .000000000
Date: Wed, 10 Nov 2010 11:02:30 -0700

[Message part 1 (text/plain, inline)]

On 11/10/2010 07:59 AM, IgnorantGuru wrote:
> $ stat -c %Z examplefile 
> 1289397609.000000000
> 
> stat (GNU coreutils) 8.6 installed from Arch Linux repos, executing in a bash shell.
> 
> This behavior changed recently - didn't used to have the .000000000 which breaks scripts that use stat.  eg
> line 297: ((: 1289301692.000000000: syntax error: invalid arithmetic operator (error token is ".000000000")

Technically, this is not a bug, since it was documented in NEWS:

  stat now outputs the full sub-second resolution for the atime,
  mtime, and ctime values since the Epoch, when using the %X, %Y, and
  %Z directives of the --format option.  This matches the fact that
  %x, %y, and %z were already doing so for the human-readable variant.

However, it has already been discussed (extensively!) on this list that
it was somewhat an undesirable change, so for the soon-to-be-released
8.7, the behavior is changing yet again:

http://lists.gnu.org/archive/html/bug-coreutils/2010-11/msg00076.html

  stat's %X, %Y, and %Z directives once again print only the integer
  part of seconds since the epoch.  This reverts a change from
  coreutils-8.6, that was deemed unnecessarily disruptive.  To obtain
  a full resolution time stamp for %X, use %.X; if you want (say) just
  3 fractional digits, use %.3X.  Likewise for %Y and %Z.

  stat's new %W format directive would print floating point seconds.
  However, with the above change to %X, %Y and %Z, we've made %W work
  the same way as the others.

so that %Z will once again omit nanoseconds, %.Z will print 9
nanoseconds, %#.Z will print as many non-zero fractional seconds as
supported by the fs, and %#.3Z will truncate to milliseconds.

-- 
Eric Blake   eblake <at> redhat.com    +1-801-349-2682
Libvirt virtualization library http://libvirt.org

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Message #11 received at 7365 <at> debbugs.gnu.org (full text, mbox):

From: IgnorantGuru <ignorantguru <at> users.sourceforge.net>
To: Eric Blake <eblake <at> redhat.com>
Cc: 7365 <at> debbugs.gnu.org
Subject: Re: bug#7365: stat bug: %Z appends .000000000
Date: Wed, 10 Nov 2010 11:24:01 -0700

Thanks for the explanation - I definitely think maintaining backward compatibility is a better approach.  There is far too much breakage of software in linux as it is.


On Wed, 10 Nov 2010 11:02:30 -0700
Eric Blake <eblake <at> redhat.com> wrote:

> On 11/10/2010 07:59 AM, IgnorantGuru wrote:
> > $ stat -c %Z examplefile 
> > 1289397609.000000000
> > 
> > stat (GNU coreutils) 8.6 installed from Arch Linux repos, executing
> > in a bash shell.
> > 
> > This behavior changed recently - didn't used to have the .000000000
> > which breaks scripts that use stat.  eg line 297: ((:
> > 1289301692.000000000: syntax error: invalid arithmetic operator
> > (error token is ".000000000")
> 
> Technically, this is not a bug, since it was documented in NEWS:
> 
>   stat now outputs the full sub-second resolution for the atime,
>   mtime, and ctime values since the Epoch, when using the %X, %Y, and
>   %Z directives of the --format option.  This matches the fact that
>   %x, %y, and %z were already doing so for the human-readable variant.
> 
> However, it has already been discussed (extensively!) on this list
> that it was somewhat an undesirable change, so for the
> soon-to-be-released 8.7, the behavior is changing yet again:
> 
> http://lists.gnu.org/archive/html/bug-coreutils/2010-11/msg00076.html
> 
>   stat's %X, %Y, and %Z directives once again print only the integer
>   part of seconds since the epoch.  This reverts a change from
>   coreutils-8.6, that was deemed unnecessarily disruptive.  To obtain
>   a full resolution time stamp for %X, use %.X; if you want (say) just
>   3 fractional digits, use %.3X.  Likewise for %Y and %Z.
> 
>   stat's new %W format directive would print floating point seconds.
>   However, with the above change to %X, %Y and %Z, we've made %W work
>   the same way as the others.
> 
> so that %Z will once again omit nanoseconds, %.Z will print 9
> nanoseconds, %#.Z will print as many non-zero fractional seconds as
> supported by the fs, and %#.3Z will truncate to milliseconds.
> 

Message #14 received at 7365 <at> debbugs.gnu.org (full text, mbox):

From: James Youngman <jay <at> gnu.org>
To: IgnorantGuru <ignorantguru <at> users.sourceforge.net>
Cc: Eric Blake <eblake <at> redhat.com>, 7365 <at> debbugs.gnu.org
Subject: Re: bug#7365: stat bug: %Z appends .000000000
Date: Thu, 11 Nov 2010 13:52:04 +0000

On Wed, Nov 10, 2010 at 6:24 PM, IgnorantGuru
<ignorantguru <at> users.sourceforge.net> wrote:
> Thanks for the explanation - I definitely think maintaining backward compatibility is a better approach.  There is far too much breakage of software in linux as it is.

FWIW, GNU findutils does the same thing.   I don't think anybody
complained about this.

James.

Message #19 received at 7365-done <at> debbugs.gnu.org (full text, mbox):

From: Jim Meyering <jim <at> meyering.net>
To: IgnorantGuru <ignorantguru <at> users.sourceforge.net>
Cc: Eric Blake <eblake <at> redhat.com>, 7365-done <at> debbugs.gnu.org
Subject: Re: bug#7365: stat bug: %Z appends .000000000
Date: Sun, 14 Nov 2010 19:09:07 +0100

IgnorantGuru wrote:
> Thanks for the explanation - I definitely think maintaining backward
> compatibility is a better approach.  There is far too much breakage of
> software in linux as it is.

coreutils-8.7 (just released) is better in this respect.
I'm marking this issue as "done".

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