Refine how to display the Apache error log with a simple command
While you hunt a bug in your code you may wish to check the error log and refine the result. If you configured a virtual host you may use individual <site>-error.log and will be easier to track some error. You may have problems with more than one live site on your machine.
But if you need to track the error log/debug by specific string use this command in the console:
tail -f /var/log/apache2/error.log | grep --line-buffered <my string here>