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EXPR(1)			  BSD General Commands Manual		       EXPR(1)

NAME
     expr -- evaluate expression

SYNOPSIS
     expr expression

DESCRIPTION
     The expr utility evaluates	expression and writes the result on standard
     output.

     All operators are separate	arguments to the expr utility.	Characters
     special to	the command interpreter	must be	escaped.

     Operators are listed below	in order of increasing precedence.  Operators
     with equal	precedence are grouped within {	} symbols.

     expr1 | expr2
	     Return the	evaluation of expr1 if it is neither an	empty string
	     nor zero; otherwise, returns the evaluation of expr2.

     expr1 & expr2
	     Return the	evaluation of expr1 if neither expression evaluates to
	     an	empty string or	zero; otherwise, returns zero.

     expr1 {=, >, >=, <, <=, !=} expr2
	     Return the	results	of integer comparison if both arguments	are
	     integers; otherwise, returns the results of string	comparison us-
	     ing 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.

     expr1 {+, -} expr2
	     Return the	results	of addition or subtraction of integer-valued
	     arguments.

     expr1 {*, /, %} expr2
	     Return the	results	of multiplication, integer division, or	re-
	     mainder of	integer-valued arguments.

     expr1 : expr2
	     The ":" operator matches expr1 against expr2, which must be a
	     regular expression.  The regular expression is anchored to	the
	     beginning of  the string with an implicit "^".

	     If	the match succeeds and the pattern contains at least one regu-
	     lar expression subexpression "\(...\)", the string	corresponding
	     to	"\1" 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.

     Parentheses are used for grouping in the usual manner.

EXAMPLES
     1.	  The following	example	adds one to the	variable a.
		a=`expr	$a + 1`

     2.	  The following	example	returns	the filename portion of	a pathname
	  stored in variable a.	 The //	characters act to eliminate ambiguity
	  with the division operator.
		expr //$a : '.*/\(.*\)'

     3.	  The following	example	returns	the number of characters in variable
	  a.
		expr $a	: '.*'

DIAGNOSTICS
     The expr utility exits with one of	the following values:
     0	     the expression is neither an empty	string nor 0.
     1	     the expression is an empty	string or 0.
     2	     the expression is invalid.

SEE ALSO
     sh(1), test(1)

STANDARDS
     The expr utility conforms to IEEE Std 1003.2 ("POSIX.2").

BSD				 July 3, 1993				   BSD

NAME | SYNOPSIS | DESCRIPTION | EXAMPLES | DIAGNOSTICS | SEE ALSO | STANDARDS

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