Korn Shell: Unix and Linux Programming Manual, Third Edition, The

Arithmetic Evaluation

The shell performs arithmetic evaluation for arithmetic substitution, to evaluate an arithmetic command, to evaluate an indexed array subscript, and to evaluate arguments to the builtin commands shift and let. Evaluations are performed using double precision floating point arithmetic. Floating point constants follow the ANSI-C programming language conventions. Integer constants are of the form [base#]n where base is a decimal number between two and sixty-four representing the arithmetic base and n is a number in that base. The digits above 9 are represented by the lower case letters, the upper case letters, @, and _ respectively. For bases less than or equal to 36, upper and lower case characters can be used interchangeably. ...