PATH vs current dir and dir sure to be not existing

POSIX mandates that an empty dir in the PATH env variable (i.e. an
initial or terminal colon, or an empty entry "...::...") be treated as
meaning the current working dir, allowing to try to execute the
searched utility there.

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.

The general rule of safety is doing:

PATH="/bin:/usr/bin:${MYSCRIPTS:-/not/existing}:/usr/pkg/bin"

but is there a pathname that is guaranteed not to exist?

Or is using "/dev/null" the choice? Or defining a special file in /dev
that will always have permissions as 0000? (and then what name? and
that will log what tried to access it.)

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