Re: who(1) exit status

[Bo Borgerson]

Andreas Schwab wrote:
> Eric Blake <address@hidden> writes:
> 
>> According to Shal-Linux-Ind on 6/23/2008 4:05 AM:
>> | Hi,
>> |
>> | who(1) exit status is always 0.
>> |
>> | $ who --v
>> | who (coreutils) 5.2.1
>>
>> Thanks for the report.  Consider upgrading - that is several years old,
>> and the latest stable version is 6.12.  But I have confirmed that the
>> issue still exists in git beyond 6.12:
>>
>> $ who /nosuch/file; echo $?
>> 0
> 
> See the comment in read_utmp:
> 
>   /* Ignore the return value for now.
>      Solaris' utmpname returns 1 upon success -- which is contrary
>      to what the GNU libc version does.  In addition, older GNU libc
>      versions are actually void.   */
>   UTMP_NAME_FUNCTION (file);
> 
> When using the utmpname/setutent/getutmp family of functions there
> really is no way to check for errors reading the file, since utmpname
> does not actually try to open it, and setutent has no return value.

Hi,

So it sounds like there's no portable way to distinguish between:

1. an error trying to look up information
2. no information to be found

Would it make sense, though, to return a nonzero exit code when output
is empty in either case?

Thanks,

Bo