expr(1)							     expr(1)








 NAME
      expr - evaluate arguments as an expression


 SYNOPSIS
      expr arguments


 DESCRIPTION
      expr takes arguments as an expression, evaluates, then writes the
      result on the standard output.  Terms in the expression must be
      separated by blanks.  Characters special to the shell must be escaped.
      Note that 0, rather than the null string, is returned to indicate a
      zero value.  Strings containing blanks or other special characters
      should be quoted.	 Integer-valued arguments can 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
	   expr \> expr
	   expr \>= expr
	   expr \< expr	  returns the result of an integer comparison if
	   expr \<= expr  both arguments are integers; otherwise returns the
	   expr != expr	  result of a lexical comparison (note that = and ==
			  are identical, in that both test for equality).


	   expr + expr	  addition of integer-valued arguments.


	   expr - expr	  subtraction of integer-valued arguments.


	   expr \* expr	  multiplication of integer-valued arguments.


	   expr / expr	  division of integer-valued arguments.


	   expr % expr	  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.  expr supports the Basic
			  Regular Expression syntax (see regexp(5)), except
			  that all patterns are ``anchored'' (i.e., begin
			  with ^) and, therefore, ^ is not a special
			  character, in that context.  Normally, the






 Hewlett-Packard Company	    - 1 -    HP-UX Release 10.20:  July 1996












 expr(1)							     expr(1)








			  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 :.


	   \(...\)	  Grouping symbols.  Any expression can be placed
			  within parentheses.  Parentheses can be nested to
			  a depth of EXPR_NEST_MAX as specified in the
			  header file <limits.h>.


 EXTERNAL INFLUENCES
    Environment Variables
      LC_COLLATE determines the collating sequence used in evaluating
      regular expressions and the behavior of the relational operators when
      comparing string values.


      LC_CTYPE determines the interpretation of text as single- and/or
      multi-byte characters, and the characters matched by character class
      expressions in regular expressions.


      LANG determines the language in which messages are displayed.


      If LC_COLLATE or LC_CTYPE is not specified in the environment or is
      set to the empty string, the value of LANG is used as a default for
      each unspecified or empty variable.  If LANG is not specified or is
      set to the empty string, a default of "C" (see lang(5)) is used
      instead of LANG.	If any internationalization variable contains an
      invalid setting, expr behaves as if all internationalization variables
      are set to "C" (see environ(5)).


    International Code Set Support
      Single- and multi-byte character code sets are supported.


 RETURN VALUE
      As a side effect of expression evaluation, expr returns the following
      exit values:








 Hewlett-Packard Company	    - 2 -    HP-UX Release 10.20:  July 1996












 expr(1)							     expr(1)








	    0	  Expression is neither null nor zero.


	    1	  Expression is null or zero.


	    2	  Invalid expression.


	   >2	  An error occurred while evaluating the expression.


 DIAGNOSTICS
      syntax error			 Operator or operand errors


      non-numeric argument		 Arithmetic attempted on a string


 EXAMPLES
      Add 1 to the shell variable a:


	   a=`expr $a + 1`


      For $a equal to either /usr/abc/file or just file, return the last
      segment of a path name (i.e., file).  Beware of / alone as an argument
      because expr interprets it as the division operator (see WARNINGS
      below):


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


      A better representation of the previous example.	The addition of the
      // characters eliminates any ambiguity about the division operator and
      simplifies the whole expression:


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


      Return the number of characters in $VAR:


	   expr $VAR : '.*'


 WARNINGS
      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 = '='


      resembles:


	   expr = = =


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


	   expr X$a = X=








 Hewlett-Packard Company	    - 3 -    HP-UX Release 10.20:  July 1996












 expr(1)							     expr(1)








 AUTHOR
      expr was developed by OSF and HP.


 SEE ALSO
      sh(1), test(1), environ(5), lang(5), regexp(5).


 STANDARDS CONFORMANCE
      expr: SVID2, SVID3, XPG2, XPG3, XPG4, POSIX.2




























































































 Hewlett-Packard Company	    - 4 -    HP-UX Release 10.20:  July 1996