The following are commonly used commands to acess files and directories:

filesystem	- An overview of the unix filesystem.
files	- An overview of unix files.
ls	- List files.
cp	- Copy files.
mv	- Move (rename) files.
rm	- Remove (delete) files.
chmod	- Set the file permissions on a file or directory.
cd	- Change current working directory.
pwd	- Print your current working directory.
mkdir	- Make a new directory.
rmdir	- Remove a directory (must be empty first).
cat	- Print files to screen.
more	- Print files to screen, one page at a time.
less	- Like more but better.
head	- Print the first few lines of a file.
tail	- Print the last few lines of a file.