expr man page on Ultrix

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expr(1)								       expr(1)

Name
       expr - evaluate expressions

Syntax
       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 operators 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	   The relop is one of < <= = != >= > and yields 1  if
			   the	indicated comparison is true, 0 if false.  The
			   comparison is numeric if both  expr	are  integers,
			   otherwise lexicographic.

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

       expr * expr
	    expr / expr
	    expr % expr
			   Yields  multiplication,  division,  or remainder of
			   the arguments.

       expr : expr

       match  string  expr
			   The matching operators and compare the string first
			   argument  with  the regular expression second argu‐
			   ment; regular expression syntax is the same as that
			   of  The  \(...\)  pattern  symbols  can  be used to
			   select a portion of the first argument.  Otherwise,
			   the matching operator returns the number of charac‐
			   ters matched (0 on failure).

       ( expr )		   Parentheses for grouping.

       To lexically compare two special characters, such as with you must pre‐
       cede  them  with identical nonspecial characters.  To lexically compare
       any two operators, such as with you must precede them  with  identical,
       nonoperator characters.	For example:
       expr "X(" ">" "X)"

       expr "S+" | expr "S-"

Examples
       The first example adds 1 to the shell variable a:
       a=`expr $a + 1`
       The second example finds the file name part (least significant part) of
       the pathname stored in variable a,
       expr $a : ´.*/\(.*\)´ ´|´ $a
       Note the quoted shell metacharacters.

Diagnostics
       The command returns the following exit codes:

       0    The expression is neither null nor 0.

       1    The expression is null or 0.

       2    The expression is invalid.

See Also
       ed(1), sh(1), test(1)

								       expr(1)
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