MFC r306719:
Document origins of expr & authors
http://minnie.tuhs.org/cgi-bin/utree.pl?file=PWB1/usr/man/man1/expr.1

PR: 173979
Approved by: bcr (mentor)
Differential Revision: https://reviews.freebsd.org/D8104

Copy head (r256279) to stable/10 as part of the 10.0-RELEASE cycle.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

Minor mdoc nits.

Whitespace cleanup:
o Wrap sentences on to new lines
o Cleanup trailing whitespace

Found with: textproc/igor
MFC after: 1 week
X-MFC-With: r232157

Fix various typos in manual pages.

Submitted by: amdmi3
PR: 165431
MFC after: 1 week

Make /bin/expr support 64bit numeric range and range checks by default,
again. This brings back the behaviour of expr in FreeBSD-4, which had been
reverted due to an assumed incompatbility with POSIX.1 for FreeBSD-5.

This issue has been discussed in the freebsd-standards list, and the
consensus was, that POSIX.1 is in fact not violated by this extension,
since it affects only cases of POSIX undefined behaviour (overflow of
signed long).

Other operating systems did upgrade their versions of expr to support
64bit range, after it had been initially brought to FreeBSD. They have
used it for a decade without problems, meanwhile.

The -e option is retained, but it will only select less strict checking
of numeric parameters (leading white-space, leading "+" are allowed and
skipped, an empty string is considered to represent 0 in numeric context.)
The call of check_utility_compat() as a means of establishing backwards
compatibility with FreeBSD-4 is considered obsolete, but preserved in
this commit. It is expected to be removed in a later revision of this
file.
Reviewed by: bde, das, jilles
MFC after: 2 month (those parts that do not violate POLA)

expr(1): Add sh(1) versions of examples, remove an incorrect example.

The three examples are better done using sh(1) itself these days.

The example
expr -- "$a" : ".*"
is incorrect in the general case, as "$a" may be an operator.

MFC after: 2 weeks

Fix markup.

Add the new standard EXIT STATUS section where appropriate.
Sort standard sections in the (documented) preferred order.

Removed harmful empty lines that crept in during the copyright
header update.

/*- or .\"- or #- to begin license clauses.

Remove BUGS section that talked about missing multibyte character support.
We have support now that the regular expression routines do.

Document missing multibyte character handling in utilities specified
by POSIX.

mdoc(7) police:

Revert to using the .Tn POSIX and .Tn ANSI instead of \*[Px] and \*[Ai]
strings; using these strings is unsafe in troff mode, as they include a
change in a font size.

Approved by: re

mdoc(7) police: markup fixes.

Approved by: re

Create a small library function, check_utility_compat(3), to determine
whether a named utility should behave in FreeBSD 4.x-compatible mode
or in a standard mode (default standard). The configuration is done
malloc(3)-style, with either an environment variable or a symlink.

Update expr(1) to use this new interface.

mdoc(7) police: markup nits.

EXPR_COMPAT should imply -e, since there is no way to specify it otherwise,
and -e reflects the historic behavior of FreeBSD's expr.

The response to my POSIX interpretation request says that `expr'
is required to be oblivious to overflow and to use the data type `long'.
(Division by zero is undefined in ISO C so it's still OK to check for it
here.) Add a new `-e' flag to get the old, more useful behavior.

Provide an environment variabloe, EXPR_COMPAT, which disables option
parsing for compatibility with old implementations.

Typo (if => of).

Add a word of caution about integer arithmetic range and overflow detection.

Fix a few formatting brainos and make the formatting of the EXAMPLES
section somewhat clearer.

Make expr POSIX-compliant, and fix some bugs. Specifically:

- expr must conform to the Utility Syntax Guidelines, so use
getopt() to eat the (non-existent) options.

- Use the Standard type intmax_t for arithmetic.

- If an argument cannot be *completely* converted to an integer, then
it is a string.

Additionally make some style cleanups near the modified lines. This
utility is still not completely style-compliant.

Remove whitespace at EOL.

Prepare for mdoc(7)NG.

mdoc(7) police: use the new features of the Nm macro.

$Id$ -> $FreeBSD$

Add cross-references to test(1) and expr(1) respectively.

PR: docs/9111
Submitted by: Josh Gilliam <josh@quick.net>

Correct use of .Nm.

Revert $FreeBSD$ to $Id$

Make the long-awaited change from $Id$ to $FreeBSD$

This will make a number of things easier in the future, as well as (finally!)
avoiding the Id-smashing problem which has plagued developers for so long.

Boy, I'm glad we're not using sup anymore. This update would have been
insane otherwise.

Fix some spelling errors.

Fix gross spelling and typographical errors pointed out by Keith Bostic.

Document the new, less restrictive, behavior of the matching operator.

Update to my latest expr (fixes bugs with comparison and matching operators)
Add man page I wrote.