This task is to determine if there is only one instance of an application running. If the program discovers that an instance of it is already running, then it should display a message indicating that it is already running and exit.

import __main__, os
 
def isOnlyInstance():
    # Determine if there are more than the current instance of the application
    # running at the current time.
    return os.system("(( $(ps -ef | grep python | grep '[" +
                     __main__.__file__[0] + "]" + __main__.__file__[1:] +
                     "' | wc -l) > 1 ))") != 0