ok [message]When used without arguments ok prints the message `ok (y/n): ` to stdout and waits for the user to enter a character followed by a line feed. If the character is `y' then the program exits with a code of 0; any other string (including enter alone) will generate an exit code of 1.
If a message is specified, it is printed to stdout (without carriage return) and the program awaits input as above.