# Re: arithmetic substitution in while loop in MKS Korn shell

**From:** David Thompson (*dat1965_at_yahoo.com*)

**Date:** 10/02/03

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Date: Thu, 02 Oct 2003 03:11:45 GMT

"Chris F.A. Johnson" <c.f.a.johnson@rogers.com> wrote

*> the MKS Korn shell is supposed to be compatible with ksh93.
*

Oh?

I don't think that's quite true. MKS provides a subset only,

but I've never seen it fully documented just what this subset

is. For example, ksh93 supports arithmetic expressions using

the (( expr )) syntax,

X=1

(( X = X + 1 ))

but MKS most definitely does not.

ksh93 has 1) arithmetic expressions and 2) arithmetic substitutions,

but MKS only has #2, ie,

1) arithmetic expression (( X = X + 1 ))

2) arithmetic substitution X=$(( X + 1 ))

OTOH, I've never seen explicit claims to be a subset of ksh93,

or be compatible with ksh93 either. Ie, this page below never

mentions ksh93,

http://www.mkssoftware.com/docs/man1/sh.1.asp

although it does mention POSIX.2 compatibility.

-- David Thompson Foster City, CA

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