The Unix commands you need to know

You need to know just a few commands to work comfortably in a Unix terminal: ls, cd, pwd, less, mkdir, cp, mv, rm.

A brief summary:

ls   list files in the current directory
ls path/to/a/directory   list files in the directory
cd path/to/a/directory   change directory
cd ../   go to the parent directory

pwd   print the current working directory

less file   view the contents of the file (press Q to exit)
cat file   print the contents of the file on the screen (stdout)

mkdir newdirectoryname   create new directory
cp file1 file2   copy file1 and call the copy file2
mv file1 file2   rename (move) file1 to file2
rmdir directoryname   remove empty directory
rm file   remove file

man command   documentation about the command

Try this Unix tutorial for more information.