EXPR(1)			 HP-UX 5.0		       EXPR(1)

     NAME
	  expr - evaluate arguments as an expression

     SYNOPSIS
	  expr arguments

     HP-UX COMPATIBILITY
	  Level:    HP-UX/STANDARD

	  Origin:   System V

	  Native Language Support:
		    8-bit filenames.

     DESCRIPTION
	  The arguments are taken as an expression.  After evaluation,
	  the result is written on the standard output.	 Terms of the
	  expression must be separated by blanks.  Characters special
	  to the shell must be escaped.	 Note that 0 is returned to
	  indicate a zero value, rather than the null string.  Strings
	  containing blanks or other special characters should be
	  quoted.  Integer-valued arguments may be preceded by a unary
	  minus sign.  Internally, integers are treated as 32-bit, 2's
	  complement numbers.

	  The operators and keywords are listed below.	Characters
	  that need to be escaped are preceded by \.  The list is in
	  order of increasing precedence, with equal precedence
	  operators grouped within {} symbols.

	  expr \| expr
	       returns the first expr if it is neither null nor 0,
	       otherwise returns the second expr.

	  expr \& expr
	       returns the first expr if neither expr is null or 0,
	       otherwise returns 0.

	  expr { =, \>, \>=, \<, \<=, != } expr
	       returns the result of an integer comparison if both
	       arguments are integers, otherwise returns the result of
	       a lexical comparison (note that = and == are identical,
	       in that both test for equality).

	  expr { +, - } expr
	       addition or subtraction of integer-valued arguments.

	  expr { \*, /, % } expr
	       multiplication, division, or remainder of the integer-
	       valued arguments.

	  expr : expr
	       The matching operator : compares the first argument
	       with the second argument which must be a regular
	       expression.  Regular expression syntax is the same as
	       that of ed(1), except that all patterns are
	       ``anchored'' (i.e., begin with ^) and, therefore, ^ is
	       not a special character, in that context.  Normally,
	       the matching operator returns the number of characters
	       matched (0 on failure).	Alternatively, the \(...\)
	       pattern symbols can be used to return a portion of the
	       first argument.

	  length expr
	       The length of expr.

	  substr expr expr expr
	       Takes the substring of the first expr, starting at the
	       character specified by the second expr for the length
	       given by the third expr.

	  index expr expr
	       Returns the position in the first expr which contains a
	       character found in the second expr.

	  match
	       Match is a prefix operator equivalent to the infix
	       operator :.

     EXAMPLES
	  1.   a=expr $a + 1

		    adds 1 to the shell variable a.

	  2.   #  For $a equal to either "/usr/abc/file" or just
	       "file"
	       expr  $a	 :  .*/\(.*\)  \|  $a

		    returns the last segment of a path name (i.e.,
		    file).  Watch out for / alone as an argument: expr
		    will take it as the division operator (see BUGS
		    below).

	  3.   #  A better representation of example 2.
	       expr  //$a  :  .*/\(.*\)

		    The addition of the // characters eliminates any
		    ambiguity about the division operator and
		    simplifies the whole expression.

	  4.   expr  $VAR  :  .*

		    returns the number of characters in $VAR.
     RETURN VALUE
	  As a side effect of expression evaluation, expr returns the
	  following exit values:
	       0    if the expression is neither null nor 0
	       1    if the expression is null or 0
	       2    for invalid expressions.

     SEE ALSO
	  ed(1), sh(1), test(1).

     DIAGNOSTICS
	  syntax error	 for operator/operand errors
	  non-numeric argument
			 if arithmetic is attempted on such a string

     BUGS
	  After argument processing by the shell, expr cannot tell the
	  difference between an operator and an operand except by the
	  value.  If $a is an =, the command:

	       expr  $a	 =  =

	  looks like:

	       expr  =	=  =

	  as the arguments are passed to expr (and they will all be
	  taken as the = operator).  The following works:

	       expr  X$a  =  X=