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