mkdir enhancement/bug? - mode & parents

[Bill McGonigle]

Hi,

I assumed this would be an FAQ, but I didn't find it on the FAQ or in 
the archives.

If I do:
   mkdir -m 777 -p a/b/c/d/e/

I would expect mkdir to make a, b, c, d, and e for me, set to 777.  
Actually, it sets a,b,c, and d to 755, the value from my umask, and e 
to 777.  I don't see an easy way to do what I expect, besides following 
up the mkdir with a chmod -R.  The info page defines this behavior 
correctly.

The POSIX spec for -p:
   mkdir -p -m $(umask -S),u+wx $(dirname dir) && mkdir [-m mode] dir
   http://www.opengroup.org/onlinepubs/007904975/utilities/mkdir.html

defines the behavior of mkdir -p in terms of mkdir -p, implying 
recursion, and the base case in the recursion has a way out as -p no 
longer applies.

If I run the specification explicity in a bash shell, expanded:
  mkdir -p -m u=rwx,g=rx,o=rx,u+wx a/b/c/d && mkdir -m 777 a/b/c/d/e
I get the results as the info page specifies.  That's good, but it's 
self-defined as it depends on the behavior of mkdir -p.

But if I spell out the recursion, with -p defined as the && of the two 
expressions, one would get, at each recursive step:

mkdir -p -m u=rwx,g=rx,o=rx,u+wx a/b/c/d && mkdir -m 777 a/b/c/d/e
  mkdir -p -m u=rwx,g=rx,o=rx,u+wx a/b/c && mkdir -m 777 a/b/c/d
    mkdir -p -m u=rwx,g=rx,o=rx,u+wx a/b && mkdir -m 777 a/b/c
      mkdir -p -m u=rwx,g=rx,o=rx,u+wx a && mkdir -m 777 a/b

because of how basename works. This would leave my permissions on 
a/b/c/d/e as 755,777,777,777,777

If someone wanted to argue that the base case for -p with no children 
was to do nothing, and let the right side of the expression prevail, I 
might buy it, in which case I'd get all 777's.  If one agrees that my 
interpretation is correct, then it's not a stretch to assume this was 
the intention, since it produces the more useful result.

Differently, mkdir seems to define -p as the recursion of the left 
expression, then &&'ing it with the right, but I think the spec is 
defining mkdir as the && of the two expressions, so both should be 
evaluated in each step.

I understand changing mkdir's behavior would tick off alot of people.  
I bring it up as a point of discussion, to point out how I got here, 
that perhaps the POSIX spec isn't as clear as it needs to be, and that 
people might expect different behaviors. Of course, if someone can 
point out how I'm be misinterpreting the spec, that would be great too.

So, after all that rambling, what would be useful would be an option to 
mkdir which would eliminate the need for the follow-up chown call and 
disambiguate the spec interpretation, say something like 
--chown-parents.

Thanks for listening,
-Bill