Re: Bug in "cmp" man page: missing exit status value

[Micah Cowan]

(2011年10月08日 19:14), David Booth wrote:
> Hi Micah & Bruce,
>
> Thanks for your attention to this.
>
> My version of cmp:
> [[
> $ cmp -version
> cmp (GNU diffutils) 2.8.1
> Copyright (C) 2002 Free Software Foundation, Inc.
>
> This program comes with NO WARRANTY, to the extent permitted by law.
> You may redistribute copies of this program
> under the terms of the GNU General Public License.
> For more information about these matters, see the file named COPYING.
>
> Written by Torbjorn Granlund and David MacKenzie.
> ]]
>
> My version of the cmp man page:
> [[
> diffutils 2.8.1                   April 2002
> CMP(1)
> ]]
>
> Note that my version of the cmp man page refers the reader to the *diff*
> info page:

<snip>

> I assumed that was intentional -- perhaps sharing the same code base --
> but now I'm wondering if that is also a bug.  In any case, I *did* check
> the info page for diff (attached), and it also fails to say anything
> about the exit status values.  But even worse, the end of the info page
> unhelpfully refers back to itself:

<snip>

That's a sure-fire symptom that info is viewing the manpage, not the
info documentation. This will tend to happen when the diff infopages are
not actually installed. This can happen as a result of improper
installation from a source package; but assuming that you simply
installed your OS vendor's packages, the most common explanation would
be that you're on some variant of Debian (such as Ubuntu, or Debian
itself), which is the only GNUish OS I'm aware of that has the habit of
separating the documentation from the binaries (ironically, this is due
to a slightly different understanding of what "free" means, which causes
them to consider many documents covered by the GNU FDL to be "unfree",
and therefore carried under a separate category of package than the
GPL-covered "free" program itself).

If you're on such a system, try "sudo apt-get install diffutils-doc" to
obtain and install the info docs.

As to "info diff", I believe this is incorrect; "info diff" and "info
cmp" both get me to the same actual info documentation; but one brings
me to the section talking about the diff program specifically, the other
brings me to the section on cmp.

Fortunately, it looks like this was changed to "info cmp" in GNU
diffutils 3.1, so there's no fix needed (as far as GNU's concerned). You
may wish to file a bug report with your OS (Debian or Ubuntu?) for them
to patch their version of diffutils 2.8 accordingly (but note that both
distributions are currently using 3.0 now in their latest versions -
fixes the "no exit status" issue, but still says "info diff" in the cmp
manpage).

Hope that helps,
-mjc