ubuntu@ip-10-45-205-254:/etc/apache2/sites-enabled$ sudo /usr/sbin/apache2 -S
[Tue Feb 17 20:56:42.325198 2015] [core:warn] [pid 2628] AH00111: Config variable ${APACHE_LOCK_DIR} is not defined
[Tue Feb 17 20:56:42.325484 2015] [core:warn] [pid 2628] AH00111: Config variable ${APACHE_PID_FILE} is not defined
[Tue Feb 17 20:56:42.325647 2015] [core:warn] [pid 2628] AH00111: Config variable ${APACHE_RUN_USER} is not defined
[Tue Feb 17 20:56:42.325791 2015] [core:warn] [pid 2628] AH00111: Config variable ${APACHE_RUN_GROUP} is not defined
[Tue Feb 17 20:56:42.325963 2015] [core:warn] [pid 2628] AH00111: Config variable ${APACHE_LOG_DIR} is not defined
[Tue Feb 17 20:56:42.339601 2015] [core:warn] [pid 2628] AH00111: Config variable ${APACHE_RUN_DIR} is not defined
[Tue Feb 17 20:56:42.340837 2015] [core:warn] [pid 2628] AH00111: Config variable ${APACHE_LOG_DIR} is not defined
[Tue Feb 17 20:56:42.341242 2015] [core:warn] [pid 2628] AH00111: Config variable ${APACHE_LOG_DIR} is not defined
[Tue Feb 17 20:56:42.341368 2015] [core:warn] [pid 2628] AH00111: Config variable ${APACHE_LOG_DIR} is not defined
AH00526: Syntax error on line 74 of /etc/apache2/apache2.conf:
Invalid Mutex directory in argument file:${APACHE_LOCK_DIR}