On Tue, Aug 23, 2016 at 05:15:25PM +0100, Stephane Chazelas wrote: > POSIX doesn't specify ((...)) (explicitely leaves it > unspecified), so is out of POSIX scope anyway. > > It was introduced by ksh88. > > There and in ksh93 (but not pdksh nor zsh) > > ksh -c '((0)); echo X' > > outputs X
You forgot the -e. Here's ksh88: $ ksh -e -c '((0)); echo X' $ uname -a HP-UX imadev B.10.20 A 9000/785 2008897791 two-user license ksh93 apparently changed its mind: $ ksh -e -c '((0)); echo X' X $ uname -a Linux wooledg 4.6.0-0.bpo.1-amd64 #1 SMP Debian 4.6.4-1~bpo8+1 (2016-08-11) x86_64 GNU/Linux > In any case, I'd go with Greg's advice to avoid "set -e".
