Re: environment / screen / X

[Marcus Brinkmann]

On Sun, May 12, 2002 at 01:15:47AM -0400, David Walter wrote:
> But I found out by ldd'ing some of the programs and verifying that the
> LD_LIBRARY_PATH was correctly configured to point to /X11R6/lib for
> the user account that ldd _failed_ to find libX11.so even with the
> correct LD_LIBRARY_PATH.

If the sgid/suid bit is set for a binary, and you don't have the permission
those bits indicate, then LD_LIBRARY_PATH is ignored.
 
> No   screen, no libX11.
> with screen, -> libX11. reported found.

Now the interesting thing is that the Hurd has a bug that makes screen leak
the utmp group permission.  screen itself is sgid+utmp, and this group
permission as the saved ID leaks through into the shell it spawns.

As a consequence, your user has utmp group permission inside screen (try it
out by running "ids" in screen).  And the sgid flag for many xterm's is
exactly to ge them utmp permissions.

As you already have those permissions, the LD_LIBRARY_PATH doesn't need to
be ignored now.  You have a shell.

Enjoy this bug as long as you can, because when we will fix it, you will get
the correct, non-functional behaviour even with screen ;)

(You could give your user root or utmp permission with addauth at any time,
if you are root, for example).

Thanks,
Marcus

-- 
`Rhubarb is no Egyptian god.' Debian http://www.debian.org brinkmd@debian.org
Marcus Brinkmann              GNU    http://www.gnu.org    marcus@gnu.org
Marcus.Brinkmann@ruhr-uni-bochum.de
http://www.marcus-brinkmann.de