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 c...@case.edu http://cnswww.cns.cwru.edu/~chet/
