On Wed, 20 Dec 2006, Uwe Dippel wrote:
> I needed some little script; and - as usual - tried it out by typing:
> i=0
> uplim=10
> while [ $i -lt $uplim ]
> do
> ((i=i+1))
> echo $i
> done
> 1
> 2
> 3
> 4
> 5
> 6
> 7
> 8
> 9
> 10
>
> So good, so far.
> So I put the history into a file; added
> #!/bin/sh
> and ran it.
> To my surprise, it is an endless loop printing 0.
> Typed again, works. Running the script: endless loop.
(( .. )) is ksh specific. Put #!/bin/ksh in your scritp and you'll be fine.
-Otto
>
> Question: What is missing in the loop ?
> FYI: I tried all those variation of $i in the arithmetic expression, but I
> won't do the trick. It works properly as line-by-line and loops endlessly
> as script.
>
> I can make it work by changing it to
> ...
> echo $((i=i+1))
> ...
> , but I still ask myself, why the arithmetic expression is not being
> evaluated within the script if not in combination with echo, e.g. ?
>
> Uwe
