WaitUntil is a small program for RISC OS computers, designed to be called from any Obey or TaskObey file. The program will then halt execution of that file until a specified condition has been satisfied, while allowing the operating system to continue multi-tasking.
Possible conditions are whether a specified file or directory exists, whether a specified system variable is set, whether a specified application is running, whether a specified file is open or closed, or simply whether a certain amount of time has elapsed.