1. Some folders cant be logged into with just cd Folder, some folders works with
cd /Folder
This is true for Usr folder
2. To find a file whose location you happen to have forgotten use: Sudo find / -name file_name
3. Apache2ctl -V is used to view info about the apache2 if it is installed. It includes info such as the configuration file location and name of file as well.
SomaBright 