List directory contents: ls

Change directory:

cd

Print working directory:

pwd

Create directory:

mkdir

Remove directory:

rmdir

Copy files/directories:

cp

Move/rename files/directories:

mv

Concatenate and display file content:

cat

Create empty file:

touch

Remove files/directories:

rm

Find files in the system:

find

Locate a command:

which

Estimate file space usage:

du

Report file system disk space usage:

df