GNU bug report logs - #8391
chmod setuid & setguid bits

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From: Ondrej Vasik <ovasik <at> redhat.com>
To: Bruno Haible <bruno <at> clisp.org>
Cc: chris <at> computersalat.de, Eric Blake <eblake <at> redhat.com>, Paul Eggert <eggert <at> cs.ucla.edu>, bug-gnulib <at> gnu.org, 8391 <at> debbugs.gnu.org
Subject: bug#8391: chmod setuid & setguid bits
Date: Mon, 05 Mar 2012 22:35:35 +0100

On Mon, 2012-03-05 at 21:20 +0100, Bruno Haible wrote:
> Paul Eggert wrote:
> > this use of "+" does not conflict with input usages like
> > "chmod +x foo".
> 
> It's because this use of '+' is easy to remember.
> "chmod +x" means "add execution permissions".
> "chmod -x" means "remove execution permissions".
> 
> You want a symbol for "assign exact permissions".
> IMO the equals sign is a more well-known symbol for assignment than '@'.
> So, how about a notation
>     chmod =755
> or
>     chmod =rw-r--r--

The only concern I have with equal sign (which was proposed by Paul as
the first candidate as well - see
http://debbugs.gnu.org/cgi/bugreport.cgi?bug=8391#50  ) is the confusion
with the equal sign in the symbolic mode specification - this one should
be for combination with numeric octal mode. Therefore @ sign was chosen
based on http://debbugs.gnu.org/cgi/bugreport.cgi?bug=8391#59 ...

However, you are right that = is more intuitive (using exact mode, when
specified as first character) - but using it for that will either change
behaviour or confuse people for 'chmod =rwx DIR' usecase, if there are
special bits on directory.

Greetings,
         Ondrej

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