Re: [[ -x ]] and root

["Colin Holmes" <colin@fuligin.loni.ucla.edu>]

Hi again,

 I started this thread looking for a way to do a [[ -x file]] while
running as root.  I got responses from this list (Zefram, mostly) to
the effect that access() was improperly functioning under Irix 5.3, as
it was under Linux.  I posted to comp.sys.sgi.bug to find out what they
thought and here are the more useful results....

Response 1:
In article <4sedhv$305q@uni.library.ucla.edu>, holmes@alzabo.loni.ucla.edu
write
s:
>  Anyone reported that the access() call in the system library
> behaves improperly with regard to root?  This has been a
> problem for me while writing root scripts under zsh.

Are you confident that zsh uses access(2) in its test -x
implementation?  That would be a mistake, I believe.

The access(2) system call is intended for use by setuid
executables, trying to determine if the real id of the process,
as opposed to the effective, could access a particular file.

Implementations of test -x should stat and look at mode bits.

Response 2:

It's not a problem, it's the way it's designed and supposed
to work.  As Paul says, access() has limited usefulness, and
in my experience, is often misused.
--

Dave Olson, Silicon Graphics   Guru and busybody at large


So, the folks at SGI think that the test ought to be performed
in a manner other than calling access().  I doubt they are going
to do anything to change the behaviour of access() so, if the zsh
group doesn't change the nature of the test underlying -x, I need
a workaround....  Any takers?

Colin.



-- 

* CJ Holmes, PhD, 			
* Dept Neurology, UCLA School of Medicine, 4238 Reed Bldg, Box 951769
* 710 Westwood Plaza, Los Angeles, CA 90095-1769
* ph 310-206-2101 fx 310-206-5518 email holmes@loni.ucla.edu