# Simple Guide for Beginners to Use Linux Command Line **Linux Directory :** 1. root : Main root user home 2. bin (Binaries) : Contain essential system binaries required for basic system operation. Ex . ls, cp, mv, cat, echo, sudo. 3. sbin (system binaries) : Stores essential binaries for system Administration. Ex . fdisk, ifconfig, reboot, shutdown. 4. etc (configuration file) : Contain system wide configuration files and scripts. Ex . /etc/passwd (user account) /etc/fstab (disk mount points) 5. var (variable data) : Stores log files, database and dynamically changing data. Ex . /var/log (system logs) /var/www (web server files) 6. usr ( user system resource) : Contains user installed programs, libraries and documation. Ex. /usr/bin/ (Non-essential user binaries) /usr/sbin/ (Non-essential system binaries) 7. home (user home directories) : Each user has a separate home directory. /home/username 8. opt (optional software) : Used for installing third party software manually. Ex . /opt/google/ (for google chrome) 9. dev (device file) : Contains device files. Ex . /dev/sda (for hard drives) 10. proc (process information) : A virtual filesystem that provide process and system information. 11. sys (Kernel and hardware info) : Contains system related information, similar to /proc. 12. media (removable media mount points) : Auto-mount location for USB drivers CDs, etc. 13. boot (boot loader files) : Stores boot-related files, including the Linux kernel and GRUB. 14. lib (libraries) : Shared libraries required by /bin and /sbin binaries. 15. tmp (temporary files) : Stores temporary files, usually deleted on reboot. 16. run (runtime data) : Stores runtime data EX . process IDs, sockets $ : for Normal User \# : For Root User Easy Linux Command Guide for New Users : The most frequently used command in Linux to List directories ```plaintext ls ``` Linux command to navigate through directories ```plaintext cd (directory name) ``` Linux command for close the current directory ```plaintext cd .. ``` Command used to create directories in Linux ```plaintext mkdir (directory name) ``` Move or rename files in Linux ```plaintext mv (file name) (give path) ``` Similar usage as mv but for copying files in Linux ```plaintext cp (file name) (give path) ``` Delete files or directories ```plaintext rm (files or directories) ``` Create blank/empty files ```plaintext touch (files name) ``` Clear the terminal display ```plaintext clear ``` Display file content on the terminal ```plaintext cat > (file name) ``` Print any text that follows the command ```plaintext echo "Write a text" ``` Linux command to display paged outputs in the terminal ```plaintext cat /(file name)|less ``` Access manual pages for all Linux commands ```plaintext man (command name) ``` For long listing ```plaintext ls -l ``` For remove empty directory ```plaintext rmdir (directory name) ``` How to delete folder directory is not empty ```plaintext rm -rf (directory name) ``` Remove all directory ```plaintext rmdir* ``` Display the user logged in to the system ```plaintext who ``` Display the name currently logged user ```plaintext whoami ``` Currently running processes ```plaintext ps ``` How to terminate processes manually ```plaintext kill (processes id) ``` To check process id ```plaintext top ``` Create symbolic links (shortcuts) to other files. ```plaintext ln ``` To create a link to another file types : **soft** and **hard link** **Hard link** : Is a mirror copy of an original file with the exact same contents. if you edit the contents of the original file, those change will be reflected in the hard link. If you delete the original file though, the hard link will still work and you can view and edit it as you would a normal copy of the original file. How to create **Hard link** : ```plaintext ln (file name) (hard link name for save) ``` **Soft link** : It points to the path of another file. If the original file is deleted, the soft link become broken. How to create a Soft link : ```plaintext ln -s (file name) (soft link name for save) ``` To display a file’s contents page by page ```plaintext cat (give path)|less ESC:q (for exit) ``` `Spacebar for see data page by page` `enter key for see data line by line` To see information about the system kernel ```plaintext uname uname -a ``` File zip and unzip command : ```plaintext zip (file name) unzip (file name) ``` Service command : is used to manage system services. ```plaintext systemctl status (service name) for the check the status systemctl start (service name) for start the service systemctl stop (service name) for stop the service systemctl restart (service name) for restart the service systemctl enable (service name) for enable the service ``` Head and Tail command ```plaintext head (file name) for see first top ten line tail (file name) for see bottom ten line ``` Sort command : Can be used to sort lines in ascending or descending order ```plaintext sort (file name) ``` Grep command : Is a powerful and versatile text search tool in Linux and unix based operating system. ```plaintext (any command with output) > |grep " text" ``` Tar command : In Linux is used to create and extract archived files. We can extract multiple different archive file. ```plaintext tar -cvf (archive name).tar filename tar -xvf filename ``` Export command : The export command in Linux and unix based operating system is used to set environment variable. ```plaintext export (variable name) = value ``` How to install service ? For Ubuntu ```plaintext sudo apt-get update -y or sudoapt-get install (service name) ``` For CentOS ```plaintext sudo yum install yum -y or Sudo yum update -y or sudo yum install (service name) -y ``` How to add new hard Disk ? * First add a new hard disk.(physically) * First switch off the machine. * Go and select Hard disk. Select Add. select Next. Select SCSI. Select Next. * Create a new virtual disk Select Next. * Store Virtual disk as a single file. * Select Disk size Select Next. * Start the machine. After that , Go to terminal. Super login user. ```plaintext fdisk -l ``` You will see ```plaintext Device Boot Start End Blocks Id System /dev/sda1 * 2048 2099199 1048576 83 Linux /dev/sda2 2099200 41943039 19921920 8e Linux LVM ``` Partition the Disk ```plaintext sudo fdisk /dev/sdb ``` * Press `n` → New partition * Press `p` → Primary * Press `1` → Partition number * Press `Enter` to accept default values * Press `w` to save changes Format the Partition ```plaintext sudo mkfs.ext4 /dev/sdb1 ``` Create a Mount Point ```plaintext sudo mkdir /mnt/newdisk (create a newfolder) sudo mount /dev/sdb1 /mnt/newdisk (to mount folder) ``` conclusion : In conclusion, understanding and utilizing the Linux command line is an essential skill for beginners and experienced users alike. This guide provides a foundational overview of the Linux directory structure and essential commands, enabling users to navigate, manage files, and perform system administration tasks effectively. By mastering these basics, users can enhance their productivity and gain greater control over their Linux systems. As you continue to explore and practice, you'll discover the full potential and flexibility that Linux offers, empowering you to tackle more complex tasks and customize your computing environment to suit your needs.