Matthew Saltzman wrote:
The conditionals && and || in bash are short-circuit, so that once a term is evaluated that determines the success or failure of the entire expression, evaluation of the remaining alternatives is skipped. In a test expression (enclosed in [ ... ]), are the conditionals -a and -o also short-circuit? The O'Reilly BASH book seems to suggest that they are not, but the description seems to me to be ambiguous.
To my knowledge, all conditionals are evaluated left-to-right. As soon as one comparison fails, there is no need to evaluate the remainder as the true-false condition has been met and the test is aborted with a "false" result. The only time the right-most comparison (or top level comparison if nested) is evaluated is if all other comparisons are true. ---------------------------------------------------------------------- - Rick Stevens, Systems Engineer rps2@xxxxxxxx - - Hosting Consulting, Inc. - - - - Diplomacy: The art of saying "Nice doggy!" until you can find a - - big enough rock. - ----------------------------------------------------------------------
