expr.1: delete misleading example

The result of the example expression would be 0 even if the operator
precedence were inverted.

Fixes PR bin/57670.

expr: improve portability, fix typo

Suggested by Robert Elz.

expr.1: sync with latest changes, improve wording

branches: 1.38.4;
Change back various occurrences of \*[Le], \*[Ge] (less/greater equal)
and \*(ua (upwards arrow) to literal "<=", ">=" and "^" whenever
appropriate (e.g., in code examples).

branches: 1.37.6;
Remove workaround for ancient HTML generation code.

Mark email addresses as mailto links, heads up by Sascha Wildner.
Move email addresses to same line as author name.
Do not split the third author entry on to a new line.
Public domain is not licensed by definition, heads up by Robert Elz.

Instruction to not split the line needs to be stated separately.

Add HISTORY section
Credit author of initial implementation in AUTHORS section
Bump date
Remove contraction highlighted by textproc/igor

Improvements: wording, punctuation, macro usage.

From patch by Bug Hunting.

Remove an unnecessary space in the manpage. Patch provided by Bug Hunting.

branches: 1.31.4;
minor usage nit

Explicitly quote | and : meant as separate operator. Kill trailing
whitespace. Don't use \Z' with obscure character entity. Reorder sections
to canonical order.

Convert TNF licenses to new 2 clause variant

branches: 1.28.24;
Grammar improvement by Patrick Welche.

Add some articles; use No instead of Li in one place
(more correct, see e.g. PostScript output); bump date for previous.

add support for 'length' keyword, for compatibility with GNU expr

Add some articles.

add a note explaining empty string matching via :
this adresses bin/23810 by VaX#n8

bump date and update copyright

spelling errors, some from Igor Sobrado in PR 19670

'NetBSD.org'

New policy: New sentences start on a new line.
Patches by Robert Elz <kre at munnari oz au>, with minimal changes by me.

rewritten in NetBSD 1.6 -> rewritten for NetBSD 1.6

Generate <>& symbolically. I'm avoiding .../dist/... directories for now.

Use standard headers, sort sections.

Quote `:' correctly.

Fix the operator precedence list to match reality. Operators were incorrectly
grouped there.

list parenthesis usage similar way as other operators
document operator precedence
rename section BUGS to COMPATIBILITY, add paragraph about -- handling

reimplement expr using lexical parser generated by yacc
highlights:
* / is treated correctly depending upon context (addresses PR # 10995)
* use 64 bit arithmetic, so expr is able to process integer values from
-(2**63) to (2**63 - 1)
* checks for integer over- & underflows added
* error messages improved, more error checking added

add AUTHOR section to manpage
add BUGS section, and mention possible drawbacks with other expr implementations

XXX the old expr treated empty string in arithmetic expressions as if it was 0
XXX this behaviour has been retained

For commands and utilities, use EXIT STATUS rather than RETURN VALUES as
appropriate (and documented in mdoc(7)).

Add 'RETURN VALUE' section header.

branches: 1.11.4;
On memory allocation failure, return 3 as per POSIX. (from OpenBSD)

Fix .Nm usage.

Winning Strategies has placed this code into the Public Domain

convert to new RCS id conventions.

Fix spelling error in Copyright notice

Fix spelling errors.

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

Document the fact that expr is POSIX.2 compliant.

Document that string comparisons are done using the locale specific
collation sequence.

Makefile

Add a manual page.