Re: status on $[arith] for eval arith vsl $((arith))??

[Chet Ramey]

On 4/7/12 4:45 PM, Linda Walsh wrote:
> 
> 
> 
> In modifying some released code on my distro,    I ran into the extensive use
> of   $[arith]  as a means for returning arithmetic evaluations of the
> expression.
> 
> I vaguely remember something like that from years ago, but never see any
> reference to
> it -- yet it works, and old code seems to rely on it -- and
> "$[(1+2)/3]"  looks cleaner than "$(((1+2)/3))".  So what's up with that?

It dates from Posix circa 1990 (1003.2d9, of which I've lost my paper
copy).  I implemented it after the Berkeley guys, mostly Marc
Teitelbaum, put it into Posix.  It ended up getting dropped in favor
of the ksh $((...)) expansion, at which point everyone deprecated the
old $[...].  I removed it from the manual sometime later, but it still
works as it always has.

Chet
-- 
``The lyf so short, the craft so long to lerne.'' - Chaucer
                 ``Ars longa, vita brevis'' - Hippocrates
Chet Ramey, ITS, CWRU    chet@case.edu    http://cnswww.cns.cwru.edu/~chet/