EXPR(1)                                                                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 operators grouped.

       _e_x_p_r _| _e_x_p_r
              yields the first _e_x_p_r if it is neither null nor  ‘0’,  otherwise
              yields the second _e_x_p_r_.

       _e_x_p_r _& _e_x_p_r
              yields  the first _e_x_p_r if neither _e_x_p_r is null or ‘0’, otherwise
              yields ‘0’.

       _e_x_p_r _r_e_l_o_p _e_x_p_r
              where _r_e_l_o_p _i_s _o_n_e _o_f < <= = != >= >, yields ‘1’  if  the  indi‐
              cated  comparison  is  true,  ‘0’  if  false.  The comparison is
              numeric if both _e_x_p_r are integers, otherwise lexicographic.

       _e_x_p_r + _e_x_p_r
       _e_x_p_r - _e_x_p_r
              addition or subtraction of the arguments.

       _e_x_p_r * _e_x_p_r
       _e_x_p_r / _e_x_p_r
       _e_x_p_r % _e_x_p_r
              multiplication, division, or remainder of the arguments.

       _e_x_p_r : _e_x_p_r
              The matching operator compares the string  first  argument  with
              the  regular expression second argument; regular expression syn‐
              tax is the same as that of _e_d(1).  The \(...\)  pattern  symbols
              can  be  used to select a portion of the first argument.  Other‐
              wise, the matching operator  yields  the  number  of  characters
              matched (‘0’ on failure).

       ( _e_x_p_r )
              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.

SEE ALSO
       sh(1), test(1)

DIAGNOSTICS
       _E_x_p_r 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.



7th Edition                     April 29, 1985                         EXPR(1)