Path: utzoo!hoptoad!pacbell!ames!apple!rutgers!tut.cis.ohio-state.edu!att!cbnewsc!woods
From: woods@cbnewsc.ATT.COM (Warren D. Swan)
Newsgroups: alt.sources
Subject: Re: chmod args
Summary: chmod has = too
Keywords: chmod
Message-ID: <1107@cbnewsc.ATT.COM>
Date: 2 Jun 89 16:32:50 GMT
References: <8923@csli.Stanford.EDU> <11680@s.ms.uky.edu> <8928@csli.Stanford.EDU> <12743@ihlpy.ATT.COM> <1953@ur-cc.UUCP> <2126@amelia.nas.nasa.gov> <8605@chinet.chi.il.us>
Reply-To: woods@cblph.ATT.COM (Warren D. Swan)
Distribution: usa
Organization: AT&T Bell Laboratories
Lines: 44

In article <8605@chinet.chi.il.us> ignatz@chinet.chi.il.us (Dave Ihnat) writes:
>>In article <12743@ihlpy.ATT.COM> bdavies@ihlpy.UUCP (55314-Davies,B.) writes:
>>Really.  *I* know what you all mean, but why does everyone teach the
>>octal way when these mnemonic ways exist that are so nice and easy to
>>understand for everyone?  Don't you all believe in abstraction?
>
>Actually, they still have two different and useful functions.  The mnemonic
>method is a mask, while using the octal is a total reset.

Whoops!  The rest of your article is tainted by this mistaken idea.  You've
either forgotten, or never learned about the = symbol in the mnemonic method.
For example:

>Old permission	Desired Permission	Octal arg.	Mnemonic arg.
>777		774			774		o-wx,o+r

Should be:                                              o=r
(3 characters either way!)

And more obviously:

>Desired Permission	Octal arg.	Mnemonic arg.
>2710			2710		u+rwx,g+xs,g-rw,o-rwx

Should be:                              u=rwx,g=xs,o=
                                         ^
                                         Could be +, but to be consistent...

The mnemonic is still longer, but doesn't take the mental gymnastics that your
expression requires.  Plus it still allows the abstraction referred to in
who-knows-whose article (the references are getting thick!).


>Finally, I firmly believe that it's an absolute necessity for even casual
>Unix users to fully understand file permissions; most security violations
>on Unix can be traced to user carelessness, either due to misunderstanding or
>simple lack of care when dealing with file permissions.

Agreed!
--
Warren D. Swan  (WooDS)     Y n n ____ __      You can't tell which way a train
AT&T Bell Laboratories     -(((((([__]/__]     went by looking at the tracks.
Naperville, Illinois       /o-OOOOO~~  oo
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