10.7 Mathematical Operators

We have seen that the C shell set command associates a value to a variable and that such values may be integers or text: for example, set a = 1 or set a = "test". The Korn shell surrounds an arithmetic operation with double parentheses: (( a = 1 )). OpenVMS uses = to equate a variable to an integer value and := or =" " to equate a variable to a string value. The OpenVMS user can perform mathematical operations on either string or integer values. The UNIX C shell permits only mathematical operations on integer variables, whereas the Korn shell will permit arithmetic on string variables if the value of the variable equates to an integer. The C shell @ metacharacter equates a variable name to the result of a mathematical operation using integer variables. Table 10-6 lists mathematical operators used by the shells.