Basics Of Linux

Introduction to LINUX Objective Linux Distribution What is Open Source? Linux principles Logging into Linux system Virtual consoles and graphical environment Terminal Changing Password Password Tips Root user Command line shortcuts Summary Linux Distributions 1984 :-The GNU Project and the Free Software Foundation. Creates open source version of UNIX utilities Creates GPL Software license enforcing open source principle 1991 :-Linus Torvalds Creates open source, UNIX-like kernel, released under GPL Ports some GNU utilities, solicits assistance online Today :-Linux kernel + GNU utilities = complete, open source, UNIX-like operating system. What is Open Source? Open Source :-Software and source code is available to all FSF specifies 4 freedoms Freedom to run program for any purpose Freedom to study and modify source code Freedom to redistribute the source code Freedom to create derivative programs Many open source licenses exist, each with different particulars. Linux principles Everything is file. (including hardware) Small, single purpose programs. Ability to chain programs together to perform complex tasks. Avoid captive user interface. Configuration data is stored in text. Logging into Linux system Login using username and password Two types of login screens : text based and graphical Text based login leaves you at shell propmt Graphical login leaves you at desktop like environment Each user has a home directory for personal file storage. User-specific configuration data is kept there. Virtual Consoles and graphical environment A typical Linux system has 6 virtual consoles and 1 graphical console Server system often has only virtual consoles. Desktops and workstations typically have both. If graphical console is inactive, can be started manually Login to virtual console and run startx Switch between virtual consoles using ctrl+alt+F[1-6] Access graphical console using ctrl+alt+F7 Terminal Terminal is shell prompt for command-line commands. Application->Accessories->Terminal Graphical terminal that supports multiple tabbed shells. ctrl+shift+t creates new tab. ctrl+PgUp/PgDn switches between tabs. ctrl+shift+c copies selected text. ctrl_shift+v pastes text to prompt. shift+PgUp/PgDn scrolls a screen up and down. Changing Password Passwords control access to system. For best security :-Change password at first log in. Keep changing password Choose password that is hard to guess. Change password :-GUI :-System->Preferences->About Me->change Password CLI :-passwd Password Tips Keep password at least 8 character long or more as far as you are comfortable. Dictionary words are very bad. Try to use combination of uppercase, lowercase letters, numbers and special characters. Real names, login names and variations should be avoided. Avoid formulas and excessive complexity. Do not use any easy to determine personal things. Root user A special administrative account. Also called as superuser Has nearly full control over system. And nearly unlimited capacity to damage it. Do not log in as root unless necessary. Normal user's potential to damage the system is very much limited. Root is able to read, write and delete almost any file. Root can change configuration of system and perform any task. Command line shortcuts Type TAB key to complete command lines. For command name, it will complete a command For arguments, it will complete file/folder name History commands :-history :-Lists all commands. history n :-Lists last n commands. Some more commands !! -repeats last command !char -repeats last command that started with char !num -repeats last command by its number Command line shortcuts continue... Advanced History tricks :-!?abc :-repeats last command containing abc !-n :-repeats a command entered n commands back ^old^new :-use to repeat last command with old changed to new Some more tricks :-Up and Down keys to scroll through previous commands ctrl+r :-search command in history Recall last argument Esc+. Alt+. !$ (valid for last command only) Summary We have learnt Linux Distributions What are Linux principles and open source. How to log in into Linux system What are virtual consoles, graphical environment and terminal. How to change password. What is root user. Some command line shortcuts with history command. THANK YOU