4.4BSD/usr/share/man/cat1/expr.0

EXPR(1)                BSD Reference Manual               EXPR(1)


NNAAMMEE
       expr - evaluate arguments as an expression

SSYYNNOOPPSSIISS
       eexxpprr arg ......

DDEESSCCRRIIPPTTIIOONN
       The  arguments  are taken as an expression.  After evalua-
       tion, 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 indicated comparison is  true,  `0'  if  false.
              The  comparison  is  numeric if both _e_x_p_r are inte-
              gers, 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 argu-
              ments.

       _e_x_p_r : _e_x_p_r
              The  matching  operator  compares  the string first
              argument with the regular expression  second  argu-
              ment; regular expression syntax 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.




7th Edition                May 31, 1993                         1








EXPR(1)                BSD Reference 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  con-
       tain `/':

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

       Note the quoted Shell metacharacters.

SSEEEE AALLSSOO
       sh(1), test(1)

DDIIAAGGNNOOSSTTIICCSS
       _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                May 31, 1993                         2