Re: ksh Emulation Not Clearing Envariables

[Chris Jepeway <jepeway@blasted-heath.com>]

>>> 	Variable assignments specified with special built-in utilities 
>>> remain
>>> 	in effect after the built-in completes; this shall not be the case
>>> 	with a regular built-in or other utility.
>>
>> Well...the variable assignment isn't occurring inside the function.
>> It's outside, put into the environment before the function is called.
>
> Did you actually read the spec?
Nope.  I read the excerpts you provided, in the belief that
you meant them to clearly support your statements.  Shoot me
for not catching that "[v]ariable assignments specified with
special built-in utilities" meant "variable assignments
preceding the command name."

> Maybe reading the `Simple Commands' section will convince you:
>
> 	If no command name results, variable assignments shall affect the
> 	current execution environment.  Otherwise, the variable assignments
> 	shall be exported for the execution environment of the command and
> 	shall not affect the current execution environment (except for special
> 	built-ins).
Yup, sure, that's pretty definitive.  What does it mean for

	X=one unset X

Nothing, I suppose.  unset will unset.  Never in a million years
would I have expected after

	X=one :

for X to persist, while after

	X=one true

X is unset.

I wonder what the original purpose was, here.  A "get out of jail
free card" that let code implementing the special built-ins slide?
These things (err, the SBIs) all look commands that *must* be 
implemented
as built-ins, so perhaps in some implementation(s) there weren't the 
hooks
to unset vars after they completed.  POSIX just codified it so 
pre-existing
implementations could remain compliant?

>>> Chet Ramey, ITS, CWRU    chet@po.cwru.edu    
>>> http://tiswww.tis.cwru.edu/~chet/
>> Me
> Chet Ramey, ITS, CWRU    chet@po.cwru.edu    
> http://tiswww.tis.cwru.edu/~chet/

Chris <jepeway@blasted-heath.com>.