chmod args

[Warren D. Swan]

In article <8605 at chinet.chi.il.us> ignatz at chinet.chi.il.us (Dave Ihnat) writes:
>>In article <12743 at ihlpy.ATT.COM> bdavies at 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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