Implement the HISTFILE and HISTAPPEND variables.

See the (newly updated) sh(1) for details.
Also add the -z option to fc (clear history).

None of this exists in SMALL shells.

Improve safety in var imports from the environment.

Add a new var flag VUNSAFE - set on all vars imported from the environment.

Add setvareqsafe() (which is to setvareq() as setvarsafe() is to setv

Improve safety in var imports from the environment.

Add a new var flag VUNSAFE - set on all vars imported from the environment.

Add setvareqsafe() (which is to setvareq() as setvarsafe() is to setvar())
and use that instead of setvareq() when processing the environment, so
errors don't cause the shell to abort. Use VUNSAFE in that call.

Add flags arguments to all var callback functions which are used when setting
variables, and pass the flags given to the setvar*() functions to those
functions, so they can act differently in different situations (if desired).
Most of them just ignore the flags.

When unsetting a variable, call setvar() to clear things (and call the
callback function) both when the variable had a value which needs to be freed,
and when unsetting a variable which wasn't unset previously, so the VUNSET
flag can be seen by that callback func.

When setting HISTSIZE, use the flags passed to determine whether to ignore
bad values (if VUNSAFE) or treat them as an error. This replaces the
earlier temporary hack to always ignore bad data there (histedit.c 1.68).

Miscellaneous associated minor changes.

These changes should largely be invisible in normal use.

show more ...

- Add command completion (from FreeBSD)
- Use EL_SAFEREAD

Now libedit supports embedded mode switch sequence, improve sh
support for them (adds PSlit variable to set the magic character).

Properly support EDITRC - use it as (naming) the file when setting
up libedit, and re-do the config whenever EDITRC is set.

PR/45069: Henning Petersen: Use prototypes from builtins.h .

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

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

Add new builtin 'inputrc' which allows keybindings to be redefined
for the current shell. From Arne H Juul in PR#10097.

Fixes from David Laight:
- ansification
- format of output of jobs command (etc)
- job identiers %+, %- etc
- $? and $(...)
- correct quoting of output of set, export -p and readonly -p
- differentia

Fixes from David Laight:
- ansification
- format of output of jobs command (etc)
- job identiers %+, %- etc
- $? and $(...)
- correct quoting of output of set, export -p and readonly -p
- differentiation between nornal and 'posix special' builtins
- correct behaviour (posix) for errors on builtins and special builtins
- builtin printf and kill
- set -o debug (if compiled with DEBUG)
- cd src obj (as ksh - too useful to do without)
- unset -e name, remove non-readonly variable from export list.
(so I could unset -e PS1 before running the test shell...)

show more ...

compile with WARNS = 2

Track $TERM and call the appropriate editline(3) routine to update the
terminal type.

change sethistsize() to take the history size as an argument so it can
be used directly by the new variable callback functions.

Merge in my changes from vangogh, and fix the x=`false`; echo $? == 0
bug.

convert to new RCS id conventions.

Add RCS ids.

44lite code