expr(1)                             CLIX                             expr(1)



  NAME

    expr - Evaluates arguments as an expression

  SYNOPSIS

    expr argument ...

  DESCRIPTION

    The expr command evaluates arguments as an expression.  The arguments are
    taken as an expression.  After evaluation, the result is written on
    stdout.  Terms of the expression must be separated by blanks.  Characters
    special to the shell must be escaped.  Note that 0 is returned to indicate
    a zero value, rather than the null string.  Strings containing blanks or
    other special characters should be quoted.  Integer-valued arguments may
    be preceded by a unary minus sign.  Internally, integers are treated as
    32-bit, 2s 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
           Returns the result of an integer comparison if both arguments are
           integers, otherwise returns the result of a lexical comparison.

    expr { +, - } expr
           Addition or subtraction of integer-valued arguments.

    expr { \*, /, % } expr
           Multiplication, division, or 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.  Regular expression
           syntax is the same as that of ed, except that all patterns are
           ``anchored'' (that is, begin with ^) and, therefore, ^ is not a
           special character, in that context.  Normally, the 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.



  2/94 - Intergraph Corporation                                              1

  expr(1)                             CLIX                             expr(1)



  EXAMPLES

    1.  Adds 1 to the shell variable a:

        a=`expr $a + 1`


    2.  Returns the last segment of a pathname (that is, file).  Watch out for
        / alone as an argument: expr will take it as the division operator
        (see NOTES below).

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


    3.  The addition of the // characters eliminates any ambiguity about the
        division operator and simplifies the whole expression.

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


    4.  Returns the number of characters in $VAR:

        expr $VAR : '.*'


  NOTES

    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 = '='

    looks like:

    expr = = =

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

    expr X$a = X=


  DIAGNOSTICS

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

    0      The expression is neither null nor 0

    1      The expression is null or 0



  2                                              Intergraph Corporation - 2/94

  expr(1)                             CLIX                             expr(1)



    2      Invalid expressions

    syntax error
           Operator/operand errors

    non-numeric argument
           Arithmetic is attempted on such a string

  EXIT VALUES

    The expr command exits with a value of 0 if successful.  If unsuccessful,
    expr returns a nonzero value.

  RELATED INFORMATION

    Commands: ed(1), sh(1)






































  2/94 - Intergraph Corporation                                              3