Index: stable/11/bin/expr/expr.1
===================================================================
--- stable/11/bin/expr/expr.1	(revision 307416)
+++ stable/11/bin/expr/expr.1	(revision 307417)
@@ -1,311 +1,327 @@
 .\" -*- nroff -*-
 .\"-
 .\" Copyright (c) 1993 Winning Strategies, Inc.
 .\" All rights reserved.
 .\"
 .\" Redistribution and use in source and binary forms, with or without
 .\" modification, are permitted provided that the following conditions
 .\" are met:
 .\" 1. Redistributions of source code must retain the above copyright
 .\"    notice, this list of conditions and the following disclaimer.
 .\" 2. Redistributions in binary form must reproduce the above copyright
 .\"    notice, this list of conditions and the following disclaimer in the
 .\"    documentation and/or other materials provided with the distribution.
 .\" 3. All advertising materials mentioning features or use of this software
 .\"    must display the following acknowledgement:
 .\"      This product includes software developed by Winning Strategies, Inc.
 .\" 4. The name of the author may not be used to endorse or promote products
 .\"    derived from this software without specific prior written permission
 .\"
 .\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 .\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 .\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 .\" IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 .\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 .\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 .\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 .\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 .\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 .\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 .\"
 .\" $FreeBSD$
 .\"
-.Dd February 25, 2012
+.Dd October 5, 2016
 .Dt EXPR 1
 .Os
 .Sh NAME
 .Nm expr
 .Nd evaluate expression
 .Sh SYNOPSIS
 .Nm
 .Op Fl e
 .Ar expression
 .Sh DESCRIPTION
 The
 .Nm
 utility evaluates
 .Ar expression
 and writes the result on standard output.
 .Pp
 All operators and operands must be passed as separate arguments.
 Several of the operators have special meaning to command interpreters
 and must therefore be quoted appropriately.
 All integer operands are interpreted in base 10 and must consist of only
 an optional leading minus sign followed by one or more digits (unless
 less strict parsing has been enabled for backwards compatibility with
 prior versions of
 .Nm
 in
 .Fx ) .
 .Pp
 Arithmetic operations are performed using signed integer math with a
 range according to the C
 .Vt intmax_t
 data type (the largest signed integral type available).
 All conversions and operations are checked for overflow.
 Overflow results in program termination with an error message on stdout
 and with an error status.
 .Pp
 The
 .Fl e
 option enables backwards compatible behaviour as detailed below.
 .Pp
 Operators are listed below in order of increasing precedence; all
 are left-associative.
 Operators with equal precedence are grouped within symbols
 .Ql {
 and
 .Ql } .
 .Bl -tag -width indent
 .It Ar expr1 Li \&| Ar expr2
 Return the evaluation of
 .Ar expr1
 if it is neither an empty string nor zero;
 otherwise, returns the evaluation of
 .Ar expr2
 if it is not an empty string;
 otherwise, returns zero.
 .It Ar expr1 Li & Ar expr2
 Return the evaluation of
 .Ar expr1
 if neither expression evaluates to an empty string or zero;
 otherwise, returns zero.
 .It Ar expr1 Bro =, >, >=, <, <=, != Brc Ar expr2
 Return the results of integer comparison if both arguments are integers;
 otherwise, returns the results of string comparison using the locale-specific
 collation sequence.
 The result of each comparison is 1 if the specified relation is true,
 or 0 if the relation is false.
 .It Ar expr1 Bro +, - Brc Ar expr2
 Return the results of addition or subtraction of integer-valued arguments.
 .It Ar expr1 Bro *, /, % Brc Ar expr2
 Return the results of multiplication, integer division, or remainder of integer-valued arguments.
 .It Ar expr1 Li \&: Ar expr2
 The
 .Dq Li \&:
 operator matches
 .Ar expr1
 against
 .Ar expr2 ,
 which must be a basic regular expression.
 The regular expression is anchored
 to the beginning of the string with an implicit
 .Dq Li ^ .
 .Pp
 If the match succeeds and the pattern contains at least one regular
 expression subexpression
 .Dq Li "\e(...\e)" ,
 the string corresponding to
 .Dq Li \e1
 is returned;
 otherwise the matching operator returns the number of characters matched.
 If the match fails and the pattern contains a regular expression subexpression
 the null string is returned;
 otherwise 0.
 .El
 .Pp
 Parentheses are used for grouping in the usual manner.
 .Pp
 The
 .Nm
 utility makes no lexical distinction between arguments which may be
 operators and arguments which may be operands.
 An operand which is lexically identical to an operator will be considered a
 syntax error.
 See the examples below for a work-around.
 .Pp
 The syntax of the
 .Nm
 command in general is historic and inconvenient.
 New applications are advised to use shell arithmetic rather than
 .Nm .
 .Ss Compatibility with previous implementations
 Unless
 .Fx
 4.x
 compatibility is enabled, this version of
 .Nm
 adheres to the
 .Tn POSIX
 Utility Syntax Guidelines, which require that a leading argument beginning
 with a minus sign be considered an option to the program.
 The standard
 .Fl Fl
 syntax may be used to prevent this interpretation.
 However, many historic implementations of
 .Nm ,
 including the one in previous versions of
 .Fx ,
 will not permit this syntax.
 See the examples below for portable ways to guarantee the correct
 interpretation.
 The
 .Xr check_utility_compat 3
 function (with a
 .Fa utility
 argument of
 .Dq Li expr )
 is used to determine whether backwards compatibility mode should be enabled.
 This feature is intended for use as a transition and debugging aid, when
 .Nm
 is used in complex scripts which cannot easily be recast to avoid the
 non-portable usage.
 Enabling backwards compatibility mode also implicitly enables the
 .Fl e
 option, since this matches the historic behavior of
 .Nm
 in
 .Fx . This option makes number parsing less strict and permits leading
 white space and an optional leading plus sign.
 In addition, empty operands
 have an implied value of zero in numeric context.
 For historical reasons, defining the environment variable
 .Ev EXPR_COMPAT
 also enables backwards compatibility mode.
 .Sh ENVIRONMENT
 .Bl -tag -width ".Ev EXPR_COMPAT"
 .It Ev EXPR_COMPAT
 If set, enables backwards compatibility mode.
 .El
 .Sh EXIT STATUS
 The
 .Nm
 utility exits with one of the following values:
 .Bl -tag -width indent -compact
 .It 0
 the expression is neither an empty string nor 0.
 .It 1
 the expression is an empty string or 0.
 .It 2
 the expression is invalid.
 .El
 .Sh EXAMPLES
 .Bl -bullet
 .It
 The following example (in
 .Xr sh 1
 syntax) adds one to the variable
 .Va a :
 .Dl "a=$(expr $a + 1)"
 .It
 This will fail if the value of
 .Va a
 is a negative number.
 To protect negative values of
 .Va a
 from being interpreted as options to the
 .Nm
 command, one might rearrange the expression:
 .Dl "a=$(expr 1 + $a)"
 .It
 More generally, parenthesize possibly-negative values:
 .Dl "a=$(expr \e( $a \e) + 1)"
 .It
 With shell arithmetic, no escaping is required:
 .Dl "a=$((a + 1))"
 .It
 This example prints the filename portion of a pathname stored
 in variable
 .Va a .
 Since
 .Va a
 might represent the path
 .Pa / ,
 it is necessary to prevent it from being interpreted as the division operator.
 The
 .Li //
 characters resolve this ambiguity.
 .Dl "expr \*q//$a\*q \&: '.*/\e(.*\e)'"
 .It
 With modern
 .Xr sh 1
 syntax,
 .Dl "\*q${a##*/}\*q"
 expands to the same value.
 .El
 .Pp
 The following examples output the number of characters in variable
 .Va a .
 Again, if
 .Va a
 might begin with a hyphen, it is necessary to prevent it from being
 interpreted as an option to
 .Nm ,
 and
 .Va a
 might be interpreted as an operator.
 .Bl -bullet
 .It
 To deal with all of this, a complicated command
 is required:
 .Dl "expr \e( \*qX$a\*q \&: \*q.*\*q \e) - 1"
 .It
 With modern
 .Xr sh 1
 syntax, this can be done much more easily:
 .Dl "${#a}"
 expands to the required number.
 .El
 .Sh SEE ALSO
 .Xr sh 1 ,
 .Xr test 1 ,
 .Xr check_utility_compat 3
 .Sh STANDARDS
 The
 .Nm
 utility conforms to
 .St -p1003.1-2008 ,
 provided that backwards compatibility mode is not enabled.
 .Pp
 Backwards compatibility mode performs less strict checks of numeric arguments:
 .Bl -bullet
 .It
 An empty operand string is interpreted as 0.
 .El
 .Bl -bullet
 .It
 Leading white space and/or a plus sign before an otherwise valid positive
 numeric operand are allowed and will be ignored.
 .El
 .Pp
 The extended arithmetic range and overflow checks do not conflict with
 POSIX's requirement that arithmetic be done using signed longs, since
 they only make a difference to the result in cases where using signed
 longs would give undefined behavior.
 .Pp
 According to the
 .Tn POSIX
 standard, the use of string arguments
 .Va length ,
 .Va substr ,
 .Va index ,
 or
 .Va match
 produces undefined results.
 In this version of
 .Nm ,
 these arguments are treated just as their respective string values.
 .Pp
 The
 .Fl e
 flag is an extension.
+.Sh HISTORY
+An
+.Nm
+utility first appeared in the Programmer's Workbench (PWB/UNIX).
+A public domain version of
+.Nm
+written by
+.An Pace Willisson Aq Mt pace@blitz.com
+appeared in
+.Bx 386 0.1 .
+.Sh AUTHORS
+Initial implementation by
+.An Pace Willisson Aq Mt pace@blitz.com
+was largely rewritten by
+.An -nosplit
+.An J.T. Conklin Aq Mt jtc@FreeBSD.org .
Index: stable/11
===================================================================
--- stable/11	(revision 307416)
+++ stable/11	(revision 307417)

Property changes on: stable/11
___________________________________________________________________
Modified: svn:mergeinfo
## -0,0 +0,1 ##
   Merged /head:r306719