Document the new, less restrictive, behavior of the matching operator.
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@ -1,3 +1,5 @@
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.\" -*- nroff -*-
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.\"
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.\" Copyright (c) 1993 Winning Strategies, Inc.
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.\" All rights reserved.
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.\"
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@ -26,7 +28,7 @@
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.\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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.\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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.\"
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.\" $Header: /b/source/CVS/src/bin/expr/expr.1,v 1.1 1993/07/20 20:16:26 jtc Exp $
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.\" $Id: expr.1,v 1.5 1993/10/04 22:06:59 jtc Exp $
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.\"
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.Dd July 3, 1993
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.Dt EXPR 1
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@ -65,7 +67,8 @@ if neither expression evaluates to an empty string or zero;
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otherwise, returns zero.
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.It Ar expr1 Li "{=, >, >=, <, <=, !=}" Ar expr2
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Returns the results of integer comparision if both arguments are integers;
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otherwise, returns the results of lexical comparison.
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otherwise, returns the results of string comparison using the locale-specific
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collation sequence.
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The result of each comparison is 1 if the specified relation is true,
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or 0 if the relation is false.
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.It Ar expr1 Li "{+, -}" Ar expr2
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@ -80,19 +83,19 @@ operator matches
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against
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.Ar expr2 ,
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which must be a regular expression. The regular expression is anchored
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to the begining of the string with an invisible
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.Dq ^ ,
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therefore
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.Dq ^
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is not a special character.
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to the begining of the string with an implicit
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.Dq ^ .
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.Pp
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If the pattern contains at lest one regular expression
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subexpression
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If the match succeeds and the pattern contains at least one regular
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expression subexpression
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.Dq "\e(...\e)" ,
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the string corresponding to
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.Dq "\e1"
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is returned;
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otherwise the matching operator returns the number of characters matched.
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If the match fails and the pattern contains a regular expression subexpression
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the null string is returned;
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otherwise 0.
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.El
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.Pp
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Parentheses are used for grouping in the usual manner.
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@ -114,7 +117,7 @@ The following example returns the number of characters in variable a.
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The
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.Nm expr
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utility exits with one of the following values:
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.Bl -tag -width Ds
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.Bl -tag -width Ds -compact
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.It 0
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the expression is neither an empty string nor 0.
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.It 1
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@ -125,7 +128,5 @@ the expression is invalid.
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.Sh STANDARDS
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The
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.Nm expr
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utility
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is expected to be
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.St -p1003.2
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compatible.
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utility conforms to
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.St -p1003.2 .
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