echo <text or $(command)> → Prints out the text again.

passwd → set a new password or change the current password.

clear → clear the terminal.

whoami → display current login user.

date <format (e.g +%Y/%m/%d %H:%M)> → display the current system date and time.

cal <parameters (e.g 5 2014 OR -3)> → display the calendar for the current month, specific month or a set of months.

bc → starts up an arithmetic calculator

man (command) → shows information about commands

history → display list of commands executed

su -(user) → login as a different user

exit → used to log out of the shell

ls -l / → display content of the root directory

1. /bin Contains user executable programs. For example, the ls program is located in /bin.
2. /sbin Contains system executable programs used by the root user and the system. For example, the clock program is located in /sbin.
3. /lib Contains shared library files used by /bin and /sbin.
4. /dev Contains special file system entries for devices attached to the system.
5. /boot Contains the Linux kernel and bootloader programs. The Linux kernel program is typically known as "vmlinuz".
6. /etc Contains system configuration files. Files contain user account information are located here.
7. /proc Contains special files pertaining to the state of the running Linux system. These files are virtual files.