Linux basics
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The document provides an overview of Linux, its kernel, and its components, highlighting its nature as an open-source operating system developed by Linus Torvalds. It outlines the importance of the GNU project, the role of daemons, and the functionality of the shell, specifically the bash shell. Additionally, it explains administrative aspects like root user permissions, swap space, command usage for changing permissions, and symbolic links.
Linux basics
- 1. Linux Basics Something you need to know -Shagun Rathore
- 2. What is Linux? 1. It is an operating system. 2. Open source software inspired by UNIX 3. First introduced by Linus Torvalds. 4. Linux is just a kernel, and a Linux distribution makes it a usable OS. 5. Secure : You no longer needed any antivirus software. 6. It is preferred OS, for computers , servers and mainframe computers, mobile devices. 7. Stable and reliable. 8. Could run non stop without any reboot for years.
- 3. Importance of GNU Project 1. GNU Project is the result of Free software movement. 2. Launched in sept 1983. 3. Complete OS is free software and it is free. 4. Intented to create a UNIX like operating system and this has created the Linux operating system. 5. Linux = Kernel + GNU Utilities.
- 4. What is Linux Kernel 1. One of the largest open source projects in the world. 2. It is a lowest level of easily replaceable software. 3. Role is to manage the hardware resources for users. 4. Responsible for interprocess communication. 5. Allow processes to run in user mode. 6. Kernel is the core of any OS, it is responsible for translating the user commands into equivalent language understood by the computer hardware.
- 5. Kernel
- 6. What is a shell 1. Shell is a user program or an environment provided for user interaction. 2. Shell is a command language interpreter. 3. It is not the part of kernel but it uses the kernel to execute the user commands. 4. Shell have different types : bash, single, con, c shell. Bash is the default shell that you will see.
- 7. Bash Bash is adopted to many linux systems Bash is - Bourne Again SHell, for GNU Operating systems.(/bin/sh) Bash has many different features, like command aliasing, completion etc. Bash combines the features of original shell as well as additional features to make it easier and more convenient to use. Bash also keeps the command history. You donât have to remember all the commands. Alias c = clear; Cat /etc/shells Echo $SHELL
- 8. What are daemons 1. Daemons are services that may not be available at the base operating system 2. Daemons are the programs that runs in background, free of user control. 3. Main task is to listen for service request and on the same time act on these requests. 4. They can be activated, by the occerence of any specific event or condition. 5. After the request served the daemons disconnects will wait for the next request 6. Demons has no control in termainal. 7. Ps -ef
- 9. What is LILO 1. LILO is a Linux Loader. 2. It is a boot loader for linux os. 3. LILO is costomiziable 4. LILO can be cofigured to boot other OS also. 5. Configuration file is lilo.conf
- 10. Main components of Linux OS Kernel Shell GUI System Utilities
- 12. Check the memory and cpu #free -m -g #vmstat . vmstat 2 6 #sar
- 13. What is a root user In windows we call the user as administrator or Admin user. It is similar as a super user / system administrator Root user has ultimate control over the linux os. Ex: access files and directories in the system Creating and managing users, accounts, and permissions. Restricted programs can be executed with the help of root user. Root is the default account every time the linux OS is installed.
- 14. What is a swap space. Swap space is used when the amount of RAM is full. Inactive pages and memory can be moved to swap space. It is not a replacement of the RAM It is created on the disk Preffered size is 2x of the physical memory used.
- 15. What are the permissions available. There are basically three levels of permission we can provide READ: Users can list and read the files WRITE: Users can modify files and create new files EXECUTE: Users can run a file or program Besides this you can have combination of all the three level of permissions
- 16. How to change permissions #chmod - symbolic and absolute #chown #chgrp #chown username filename #chmod +rw filename #chmod 777 filename -+= RWE - 421
- 17. What are symbolic links These links are similar to shortcuts in Windows, also called as soft links These links can point to either programs or files or directories: but do not contain the data of the file.
- 18. Thank You...