Re: PATH vs current dir and dir sure to be not existing

[tlaronde%kergis.com@localhost]

On Sat, Sep 28, 2024 at 06:24:58PM +0700, Robert Elz wrote:
>     Date:        Sat, 28 Sep 2024 10:33:55 +0200
>     From:        <tlaronde%kergis.com@localhost>
>     Message-ID:  <Zve_cyjTmZAq4fkF%kergis.com@localhost>
> 
>   | This does mean that one user setting a PATH with variables:
>   |
>   | PATH="/bin:/usr/bin:$MYSCRIPTS:/usr/pkg/bin"
>   |
>   | if MYSCRIPTS is not defined, will end up including the current working
>   | dir in his PATH, while it was not the intention.
> 
> Yes.   The expansion happens before the value is assigned to
> the variable.   There is no difference between that and explicitly
> including ::
> 
>   | The general rule of safety is doing:
>   | PATH="/bin:/usr/bin:${MYSCRIPTS:-/not/existing}:/usr/pkg/bin"
> 
> You could, but that would be wasteful.
> 
> Better would be:
> 
>   PATH="/bin:/usr/bin:${MYSCRIPTS:+${MYSCRIPTS}:}/usr/pkg/bin"
> or
>   PATH="/bin:/usr/bin${MYSCRIPTS:+:${MYSCRIPTS}}:/usr/pkg/bin"
> 
> whichever you prefer (they are essentially the same thing).
> 
> Why stick an entry in PATH that you intend not to be used?

Since I'm writing a pathsearch.7 to explain the PATH_SEARCH_OPT
option(s) for "qualified filenames" (searching in PATH for "dk/ctl", 
"vect/in/dxf" etc.), Il will add your suggestion of expanding with a
colon only if defined. Neat. 

Best,
-- 
        Thierry Laronde <tlaronde +AT+ kergis +dot+ com>
                     http://www.kergis.com/
                    http://kertex.kergis.com/
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