/sbin/usermod - modify a user account
which - shows path of the command you are using
date - shows the date and can format it with the options
file - shows what kind of file it is
head - print top of file
tail - print bottom of a file
cat - print the whole file
mkdir - create a directory
rmdir - remove a dir
pwd - list your current working directory
cd - no args - takes me home
cd - - takes you to your last directory
cd .. - go back one directory
cd . - go to this current directory
ls -a - list hidden files
ls -l - ls long listing
ls -laF - long hidden and type
cp - copy a file
mv - move a file
rm - remove file
mkdir - make a directory
mkdir -p - make a dir
touch - create an empty file