1. Module 1 - Introduction to Linux

2. Users must log-in Linux is case sensitive File and Directories naming conventions (No spaces!) Files and Directories starting with a dot (.) are hidden Linux Basics

3. Linux Users There are two kinds of users in Linux: 1. An Administrator (root) and only one. 2. Regular Users (Every one beside root) Services and Daemons have a unique user name to operate the service/daemon on their behalf. The first user in the system is root (UID 0) and the first regular user will be created with UID of 500. Services and Daemons are granted UID from 1->499

4. root (AKA Super User) is the system administrator with unlimited privileges (God) The root user has the unique User Identification Number (UID) of 0 (zero) The Linux prompt (Shell Prompt) ends with a # sign when we are logged in as the root user Linux Users

5. Regular Users have very limited privileges in the system. Regular Users are granted UID starting at 500 and above. The Linux prompt (Shell Prompt) ends with a $ sign when we are logged in as a regular user Linux Users

6. Can you “talk” in 000111110000110101001 ?! In Linux, the shell is a program that interprets commands and acts as an intermediary between the user and the inner workings of the operating system. The Linux SHELL

7. On most Linux systems, there are several shells available. For the average user, they offer similar functionality, but each has different syntax and capabilities. Most shells fall within one of two classes: those descended from the Bourne shell (i.e. sh), which first appeared in Version 7 Unix, and those from the C Shell (i.e. csh), which made its debut in BSD. Nearly every Linux system has these two shells installed, but may also have several others

8. The Linux SHELL SHELL: sh, csh, ksh and bash Bourne Again Shell: bash Switching shells is easy (when we are switching a shell we are actually opening a new Sub Shell under our original shell)

9. The Linux SHELL We can find the system default shell by echoing the variable: # echo $SHELL We can find the shell we are currently on by echoing the following variable: # echo $0 To close a shell simply issue the command: # exit

10. Which Linux are you on ? Find your Operating System name: # cat /etc/issue ( the cat command shows us a text file on our screen) Find your Kernel Version and CPU architecture: # uname -a Find the system host name: # hostname

11. The Linux SHELL Command Structure Command Options path # ls -l /home # ls -l -a /tmp # ls -al /var

12. The Linux man command Every command in the system has a manual To read this manual issue the command: # man [Command Name] # man ls We can search for a specific word in all the manuals descriptions by using the following option: # man –k [specific word] # man –k partition Search inside the manual with / and exit with q

13. Who are you and where are you ? Find who are you: # whoami # id Find where are you: # pwd

14. Shut Down Linux Issue the following command to shut down the system: # shutdown -h now