fix regression exit1: Don't exec the last command in a subshell if it has
trap[0] (trap EXIT) set. Fork instead to give the shell a chance to execute
the trap when it is done.

Revert previous commit that fixes PR/36079 (shell misses exit trap), because
the fix causes $! to point to the wrong process in pipelines, which is worse.

PR/36079: M. Levinson: Disable the optimization of not forking for the last
command in a subshell, otherwise we miss the exit trap.

show better quoting output for sh -x, from Aleksey Cheusov

Revert revisions 1.91 and 1.92. The POSIX spec about the correct behaviour
is contradictory at best. And these changes seem to cause more problems
that they are worth.

Fix two more cases of bad handling of "set -e":
- false && false
- false || false

Fix another problem with "set -e": "! true" should terminate the shell.

Port revision 1.44 of "src/bin/sh/eval.c" from FreeBSD to fix PR bin/38584.
Reviewed by Michael van Elst.

Fix inconsistent definitions

sprinkle volatile.

Coverity CID 3384: Don't close -1.

PR/33281: Martin J. Laubach: Prevent core-dump on "echo abc | { }". bash
prints and error and ksh prints nothing. We go the ksh way.

Coverity CID 2479: Clarify confusion about uninitialized variable in the
presence of setjmp/vfork.

Revert part of the previous commit. We cannot fix the problem by not waiting.
The problem is that the subshell code is not doing redirections properly.

Don't wait for a background job in a subshell when we are set to EV_EXIT.
While I am here, call forkshell() explicitly FORK_FOO flags instead of
depending in FORK_FG == 0 and FORK_BG == 1.

Mark temp_path volatile so that it won't get clobbered after longjmp.
(Also appeases gcc -Wuninitialized.)

Fix printing of invalid commandname after certain types of errors on builtins.
Fixes bug bin/29410 in head.
All of /bin/sh needs pulling up into 2.0

Pass WARNS=3

Make "set -e" once again provide the behavior documented in the man page,
which was unnecessarily changed in revision 1.50 while fixing other bugs.
That is, exit the shell if the last command in a ||

Make "set -e" once again provide the behavior documented in the man page,
which was unnecessarily changed in revision 1.50 while fixing other bugs.
That is, exit the shell if the last command in a || or && compound statement
is not short-circuited, and exits with a false status. I.e., the following
will cause the shell to exit:

set -e
false || false

While this is not the prescribed behavior in SUSv3, it is what our man page
documents, and it is what all of the following implementations do:

NetBSD /bin/ksh (pdksh)
bash
zsh
Solaris 9 /bin/sh
Solaris 9 /usr/xpg4/bin/sh
Solaris 9 /usr/bin/ksh
Tru64 /bin/sh
HP/UX 11 /bin/sh

The "standard" seems to be wrong in this instance.

show more ...

Correctly apply IFS to unquoted text in ${x-text}.
Fixes PR/26058 and the 'for i in ${x-a b c}; do ...' and ${x-'a b' c}.
I can't find a PR for the latter problem.
Regression test goind in shortly.

No functional changes (intended).
Rename some variables, add some comments, and restructure a little.
In preparation for fixing "set ${x-a b c}" and friends.

Ensure that fd 0, 1 and 2 are not used for the local end of pipelines.
Fixes PR bin/25395

Add '\n' to "fork failed" trace messages.

Move UCB-licensed code from 4-clause to 3-clause licence.

Patches provided by Joel Baker in PR 22249, verified by myself.

use bounded string op