From: Andrew Walrond <andrew@...>
Date: 2003-08-30T15:51:56+09:00
Subject: Re: File.chown removes setuid permission

>
>     Andrew> Is this behaviour deliberate, or a bug? The chown binary
>     Andrew> from gnu coreutils does not do this.
>
> You don't say what platform you are running on, but "man 2 chown" on
> my RH8 box says (in part):
>
>        When  the  owner  or  group of an executable file are changed by a
non-
>        super-user, the S_ISUID and S_ISGID mode bits are cleared.  POSIX
does
>        not  specify  whether this also should happen when root does the
chown;
>        the Linux behaviour depends on the kernel version.  In case of  a
non-
>        group-executable  file  (with  clear S_IXGRP bit) the S_ISGID bit
indi-
>        cates mandatory locking, and is not cleared by a chown.
>
> so Ruby is just doing what the system call does.
>

Thanks Daniel. This not only answers my question, but brings to my notice
the mysterious lack of man2 manual pages on my system ;)

I guess /bin/chown must explicitly save the permissions then reset them
after the call to chown()

Thanks

Andrew Walrond