2016-08-12 14:22:32 -0400, Chet Ramey: [...] > The relevant change was probably the change in the set of commands to which > `set -e' applies. The (( command (among others) was added to that list > in bash-4.1. The change was the result of Posix changing the semantics > of the errexit option and expanding its scope from simple commands to > all commands. > > The (( command returns 1 if the expression evaluates to 0. When `level' is > 0, level++ returns a 0 value, and (( returns a status of 1. [...]
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 For: ksh -ec '[[ -z . ]]; echo X' I see a difference between ksh88 (Solaris /usr/bin/ksh) which displays the X (like bash<4.1) and ksh93 (u+) which doesn't any more. In any case, I'd go with Greg's advice to avoid "set -e". -- Stephane
