${var:1:1:=y}

[Ray Andrews <rayandrews@eastlink.ca>]

We can of course do this:

     variable=${var:=xy}

I'm wanting the naive expansion of that syntax to do this:

     variable=${var:1:1:=y}

... but it doesn't work. Can something like that be done?
At the moment I'm doing this:

     variable=${var:1:1}
     [ -n "$variable" ] || variable=y

... which is perfectly fine, but the above pseudosyntax would be elegant 
if it could be made workable.


And I found something that puzzles me:


    test ()
    {
       echo $1
       echo ${1:0:1}
       /bin/echo ${1:0:1}
       echo ${1:1:1}
       echo ${1:0:1}${1:1:1}
       echo ${1:1:1}${1:0:1}
    }

    $ test -a

    -a
    [nothing]
    -
    a
    -a
    a-

... If I entered a valid switchofcourse I'd expect that to be eaten
but a solitary dash? Bug?  /bin/echo behaves as I'd expect.