Mastering Essential Linux Command Line Tools and Techniques

Introduction

The command line interface (CLI) in Linux offers a powerful and efficient way to interact with the operating system. This article will guide you through essential command line tools and techniques in Linux.

From basic navigation and file manipulation to process management, you’ll gain a solid foundation in using the command line effectively. By mastering these essential skills, we become more proficient in managing our Linux systems and executing various tasks efficiently.

1. Changing Directories:
   • cd command: Change to a specific directory. For example, cd /path/to/directory moves to the specified directory.
   • cd .. command: Move up one directory level. For instance, cd .. moves to the parent directory.
     
     
2. Listing Files and Directories:
   • ls command: List files and directories in the current directory. Use options like -l for a detailed list and -a to include hidden files.
     
     
3. Creating Directories and Files:
   • mkdir command: Create a new directory. For example, mkdir new_directory creates a directory named “new_directory”.
   • touch command: Create a new empty file. Use touch filename to create a file named “filename”.
     
     
4. Copying Files and Directories:
   • cp command: Copy files and directories. For instance, cp file.txt /path/to/destination copies “file.txt” to the specified destination.
   • cp -r command: Copy directories and their contents recursively. Use cp -r directory /path/to/destination to copy the directory and its contents.
     
     
5. Moving and Renaming Files and Directories:
   • mv command: Move or rename files and directories. For example, mv file.txt /path/to/destination moves the file to the specified destination. Use mv oldname newname to rename a file or directory.
     
     
6. Removing Files and Directories:
   • rm command: Remove files. For instance, rm file.txt deletes the specified file.
   • rm -r command: Remove directories and their contents recursively. Use rm -r directory to delete the directory and its contents.
     
     
7. Searching for Files and Text:
   • find command: Search for files and directories based on various criteria. For example, find /path/to/search -name filename searches for a file named “filename” in the specified path.
   • grep command: Search for text patterns within files. Use grep pattern file.txt to search for “pattern” in “file.txt”.
     
     
8. Viewing File Contents:
   • cat command: Display the contents of a file. For instance, cat file.txt shows the contents of “file.txt”.
   • less command: View file contents page by page. Use less file.txt to view the contents and navigate using the arrow keys or the Page Up/Page Down keys.
     
     
9. Managing Processes:
   • ps command: Display information about running processes. Use options like ps aux to show a detailed list of all processes, including system and user processes.
   • top command: Monitor real-time information about running processes, including CPU and memory usage. Press q to exit the top command.
     
     
10. Process Control:
    • kill command: Terminate a process by its process ID (PID). For example, kill PID terminates the process with the specified PID.
    • killall command: Terminate processes by their name. Use killall process_name to terminate all processes with the specified name.
      
      
11. Process Prioritization:
    • nice command: Launch a command with a specific priority. For instance, nice -n 10 command starts the command with a lower priority (higher nice value).
    • renice command: Change the priority of running processes. Use renice priority PID to adjust the priority of a running process.
      
      
12. Background and Foreground Execution:
    • & operator: Execute a command in the background. For example, command & runs the command in the background, allowing you to continue using the terminal.
    • fg command: Bring a background process to the foreground. Use fg %job_number to resume a background process.
      
      
13. Monitoring Process Resources:
    • htop command: Interactive process viewer with real-time resource monitoring. It provides a more user-friendly and feature-rich alternative to top.
    • atop command: Advanced system and process monitor that records resource usage. Use atop to view historical information about processes and system activity.
      
      
14. Process Information:
    • /proc directory: Explore the /proc directory to access detailed information about processes. Each process has a corresponding directory with its process ID (PID).