Basic Linux Commands: A Comprehensive Guide.

Linux System Commands: A Comprehensive Guide

Aim :

Gain knowledge about Linux system commands.

Linux System Commands: A Comprehensive Guide

Understanding and mastering Linux system commands is crucial for effective system administration and development. This guide will walk you through some fundamental Linux commands to enhance your command-line skills.

Guidance on How to Use:

Prerequisite:

Ensure that your system has the necessary permissions to execute commands.

1. Update the package list using the following command:

   sudo apt update

Explore these fundamental Linux commands to improve your command-line proficiency:

• User Management

  1. Add a new user :

     sudo useradd -m username

     Creates a new user with the specified username and home directory.

  2. Change password for a specific user:

     sudo passwd username

     Changes the password for the specified user.

  3. Delete a user :

     sudo userdel -r username

     Deletes the specified user and removes the home directory and mail spool.

  4. List all users:

     cat /etc/passwd

     Displays a list of all users on the system.

  5. Change user:

     su username

     Switches to the specified user account.

  6. Change user and open a new shell:

     su - username

     Switches to the specified user and opens a new login shell.

• File Manipulation

  1. Create an empty file:

     touch new_file.txt

     Creates a new, empty file with the specified name.

  2. Edit a file using the Nano text editor:

     nano file.txt

     Opens the Nano text editor for editing the content of the specified file.

  3. Display the first 10 lines of a file:

     head file.txt

     Shows the first 10 lines of the specified file.

  4. Display the last 10 lines of a file:

     tail file.txt

     Shows the last 10 lines of the specified file.

  5. Compress a file using gzip:

     gzip file.txt

     Compresses the specified file using gzip.

  6. Extract files from a tar archive:

     tar -xvf archive.tar

     Extracts files from a tar archive.

  7. List files with human-readable sizes and sort by size and date:

     ll -h --sort=size,date

• Directory Manipulation

  1. Create a new directory:

     mkdir new_directory

     Creates a new directory with the specified name.

  2. Remove an empty directory:

     rmdir empty_directory

     Removes an empty directory.

  3. List files in the current directory and subdirectories:

     ls -R

     Lists files and directories recursively.

  4. Copy a directory and its contents:

     cp -r source_directory destination

     Copies the source_directory and its contents to the specified destination.

  5. Move or rename a directory:

     mv old_directory new_directory

     Moves or renames the specified directory.

  6. Show directory size:

     du -sh /path/to/directory

     du -sh *| sort -h

     Displays the size of the specified directory.

• System Level Commands

  1. Show available memory and swap space:

     free -m

     Displays information about the system's memory and swap space in megabytes.

  2. Display disk space usage by directories:

     du -h --max-depth=1 /

     Shows disk space usage for top-level directories in the root filesystem.

  3. Display system information:

     uname -a

     Shows detailed information about the system.

  4. Display and update sorted information about system processes:

     top

     Displays real-time information about system processes.

  5. Display information about running processes:

     ps aux

     Lists all running processes on the system.

  6. Show disk space usage for each partition:

     df -h

     Displays disk space usage information for each partition.

• Network Related Commands

  1. Show network interface information:

     ifconfig

     Displays information about all network interfaces on the system.

  2. Display routing table:

     route -n

     Shows the kernel routing table, including destination, gateway, and interface information.

  3. Search for files with a specific name:

     find /path/to/search -name filename.txt

     Searches for files with the specified name in the specified directory and its subdirectories.

     Find the file named "restore_database.sh" in the entire filesystem:

     sudo find / -name restore_database.sh 2>/dev/null

  4. Filter and transform text with awk:

     awk '{print $2}' file.txt

     Prints the second column of a space-separated file.

  5. Replace text in a file using sed:

     sed 's/old_text/new_text/' file.txt

     Replaces occurrences of "old_text" with "new_text" in the file.

Verification:

Verify your Linux distribution information:

lsb_release -a

Written by: A.M.Rinas

Contact: mohomadrinas00@gmail.com