# 2.11BSD#431 - /usr/man/cat1/expr.0

    EXPR(1)             UNIX Programmer's Manual		  EXPR(1)

    NAME
         expr - evaluate arguments as an expression

    SYNOPSIS
         expr arg ...

    DESCRIPTION
         The arguments are taken as an expression.	After evaluation,
         the result is written on the standard output.  Each token of
         the expression is a separate argument.

         The operators and keywords are listed below.  The list is in
         order of increasing precedence, with equal precedence opera-
         tors grouped.

         expr | expr
    	  yields the first expr if it is neither null nor `0',
    	  otherwise yields the second expr.

         expr & expr
    	  yields the first expr if neither expr is null or `0',
    	  otherwise yields `0'.

         expr relop expr
    	  where relop is one of < <= = != >= >, yields `1' if the
    	  indicated comparison is true, `0' if false.  The com-
    	  parison is numeric if both expr are integers, otherwise
    	  lexicographic.

         expr + expr
         expr - expr
    	  addition or subtraction of the arguments.

         expr * expr
         expr / expr
         expr % expr
    	  multiplication, division, or remainder of the argu-
    	  ments.

         expr : expr
    	  The matching operator compares the string first argu-
    	  ment with the regular expression second argument; regu-
    	  lar expression syntax is the same as that of ed(1).
    	  The \(...\) pattern symbols can be used to select a
    	  portion of the first argument.  Otherwise, the matching
    	  operator yields the number of characters matched (`0'
    	  on failure).

         ( expr )
    	  parentheses for grouping.

    Printed 11/26/99	 April 29, 1985                         1

    EXPR(1)             UNIX Programmer's Manual		  EXPR(1)

         Examples:

         To add 1 to the Shell variable a:

    	  a=`expr $a + 1`

         To find the filename part (least significant part) of the
         pathname stored in variable a, which may or may not contain
         `/':

    	  expr $a : '.*/\(.*\)' '|' $a

         Note the quoted Shell metacharacters.

    SEE ALSO
         sh(1), test(1)

    DIAGNOSTICS
         Expr returns the following exit codes:

    	  0    if the expression is neither null nor `0',
    	  1    if the expression is null or `0',
    	  2    for invalid expressions.

    Printed 11/26/99	 April 29, 1985                         2

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