EXPR(1)                              BSD                               EXPR(1)



NAME
     expr - evaluate arguments as an expression

SYNOPSIS
     expr arg ...

DESCRIPTION
     The arguments are taken as an expression.  After evaluation, expr writes
     the result on the standard output.  Each token of the expression is a
     separate argument.

OPERATORS AND KEYWORDS
     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
                  Where relop is one of < <= = != >= >, yields "1" if the
                  indicated comparison is true; "0" if false.  The comparison
                  is numeric if both exprs are integers, otherwise it is
                  lexicographic.

     expr  + expr
     expr  - expr Addition or subtraction of the arguments.

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

     expr : expr  The matching operator compares the string first argument
                  with the regular expression second argument; regular
                  expression syntax is the same as that of ed(1).  You can use
                  the \(...\) pattern symbols 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.

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.

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

SEE ALSO
     csh(1), sh(1), test(1)