Handy Linux tips

`dirname`, nested commands, and following links:
cd $(dirname $(readlink -f $(which java)))/../..
There's also `hostname` to extract the filename alone.

~/.bash_profile will execute on login
~/.bashrc will execute every time bash is started

To remove ~/.sudo_as_admin_successful:
https://askubuntu.com/questions/22607/remove-note-about-sudo-that-appears-when-opening-the-terminal