Re: Unsetting a variable that was not previously set

[Peter Stephenson <pws@csr.com>]

Vincent Lefevre wrote:
> zsh should return an exit status 0 when unsetting a variable that was
> not previously set.
>
> See
>   http://www.opengroup.org/onlinepubs/007904975/utilities/unset.html

I think you're probably right, but it's not completely clear.  The page
you quote explicitly says:

EXIT STATUS

     0
        All name operands were successfully unset.
    >0
        At least one name could not be unset.

Now, if it doesn't exist, it can't be unset, but I think by `unset' they
mean `rendered such that it is not set whether or not it was before',
which is your interpretation.

> "Unsetting a variable or function that was not previously set shall
> not be considered an error and does not cause the shell to abort."

It doesn't cause the shell to abort currently.  The terminology in the
introduction does suggest `error' is more or less synonymous with
`non-zero return code', but I can find no normative indication of
whether this applies to the language used for the special builtins.

Probably someone should request a clarification.

-- 
Peter Stephenson <pws@csr.com>                  Software Engineer
CSR Ltd., Science Park, Milton Road,
Cambridge, CB4 0WH, UK                          Tel: +44 (0)1223 692070


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