Re: bin/49595: unset built-in exits with failure if parameter not set

[David Holland <dholland-bugs%netbsd.org@localhost>]

The following reply was made to PR bin/49595; it has been noted by GNATS.

From: David Holland <dholland-bugs%netbsd.org@localhost>
To: gnats-bugs%NetBSD.org@localhost
Cc: 
Subject: Re: bin/49595: unset built-in exits with failure if parameter not set
Date: Mon, 10 Oct 2016 01:13:00 +0000

 On Thu, Jan 22, 2015 at 04:10:00AM +0000, william%25thandclement.com@localhost wrote:
  > NetBSD's /bin/sh is the only shell with this behavior I've
  > found. I've tested /bin/sh on AIX 7, Solaris 11.1, OpenBSD 5.5, OS
  > X 10.2 (BETA), FreeBSD 9.0, and Ubuntu 14.04.
  > 
  > I suppose one could interpret NetBSD's behavior as conforming. But
  > I find it leads to unnecessarily complex code like `unset FOO ||
  > true` or `[ "${FOO-unset}" = "unset" ] || unset FOO`
  > 
  > >How-To-Repeat:
  > Following script should print "OK".
  > 
  > #!/bin/sh
  > FOO=bar
  > unset FOO
  > set -e
  > unset FOO
  > printf "OK\n"
 
 ok, all this is about sh, but...
 
  > >Fix:
  > Remove the following from c_unset in ksh/c_sh.c:
  > 
  > if (!(vp->flag & ISSET))
  >         ret = 1;
 
 ...that's about ksh.
 
 So are you talking about sh or ksh? Currently, sh does not exhibit
 this behavior, but ksh does.
 
 -- 
 David A. Holland
 dholland%netbsd.org@localhost