Re: Group ID

[Michael Wardle <michael.wardle@adacel.com>]

On Thursday, February 20, 2003 01:05, Russell Shaw wrote:
> When a program access a config file, does it use the group ID of the
> programs own binary, or can it be set differently from within the
> program?

If the SGID bit is not set on the executable (normal), the program 
inherits the permissions of the user who invoked the executable, and so 
the permissions of the user's primary group.

If the SGID bit is set on the executable (abnormal), the program 
inherits the permissions of the group that owns the executable file.

A process can access a file using a different group by first calling 
setgid() or setegid() if it has the necessary permissions.

Inside a program, you can test what permissions you have by using calls 
such as access() and stat().  If you are unable to edit and recompile 
the program, you could try watching what calls it makes with strace.

Hope this helps

-- 
Michael Wardle
Adacel Technologies