Here are some essential Linux commands that are frequently used in DevOps for managing systems, automating tasks, and deploying applications:

1. File and Directory Management

• ls: List files and directories.
  

   ls -la  # List all files with detailed information
  

• cd: Change directory.
  

   cd /path/to/directory  # Navigate to a specific directory
  

• cp: Copy files or directories.
  

   cp file1.txt file2.txt  # Copy file1.txt to file2.txt
   cp -r /src /dest  # Copy a directory recursively
  

• mv: Move or rename files and directories.
  

   mv oldname.txt newname.txt  # Rename a file
   mv /src /dest  # Move a file or directory
  

• rm: Remove files or directories.
  

   rm file.txt  # Remove a file
   rm -rf /path/to/dir  # Remove a directory recursively
  

2. File Viewing and Editing

• cat: Concatenate and display file content.
  

   cat file.txt  # Display file content
  

• less or more: View large files one screen at a time.
  

   less largefile.log  # View large files
  

• grep: Search for a pattern within files.
  

   grep "pattern" file.txt  # Search for a pattern in a file
   grep -r "pattern" /path  # Recursively search in a directory
  

• nano, vi, vim: Text editors for editing files.
  

   nano file.txt  # Open file in nano editor
   vi file.txt  # Open file in vi editor
  

3. System Monitoring and Process Management

• top: Display real-time system information, including running processes.
  

   top  # Display running processes and system information
  

• htop: An enhanced version of top (requires installation).

• ps: Display information about running processes.
  

   ps aux  # List all running processes
  

• kill: Terminate a process.
  

   kill -9 PID  # Forcefully terminate a process with the specified PID
  

• df: Show disk space usage.
  

   df -h  # Show disk space usage in human-readable format
  

• du: Show directory space usage.
  

   du -sh /path/to/dir  # Show size of a directory
  

4. Networking

• ifconfig or ip: Display or configure network interfaces.
  

   ifconfig  # Display network interface information
   ip addr  # Display IP addresses
  

• ping: Test network connectivity.
  

   ping google.com  # Ping Google to test connectivity
  

• netstat: Network statistics and connections.
  

   netstat -tuln  # List all listening ports
  

• curl: Transfer data from or to a server.
  

   curl http://example.com  # Fetch a web page
  

• wget: Download files from the web.
  

   wget http://example.com/file.zip  # Download a file
  

5. User and Permissions Management

• sudo: Execute a command as another user, typically root.
  

   sudo command  # Run a command with elevated privileges
  

• chmod: Change file or directory permissions.
  

   chmod 755 file.sh  # Set file permissions
  

• chown: Change file or directory ownership.
  

   chown user:group file.txt  # Change owner and group of a file
  

• useradd / userdel: Add or delete a user.
  

   sudo useradd username  # Add a new user
   sudo userdel username  # Delete a user
  

• passwd: Change a user’s password.
  

   passwd username  # Change password for a user
  

6. Archiving and Compression

• tar: Archive files.
  

   tar -cvf archive.tar /path/to/dir  # Create a tar archive
   tar -xvf archive.tar  # Extract a tar archive
  

• zip / unzip: Compress or decompress files.
  

   zip archive.zip file.txt  # Compress a file into a zip archive
   unzip archive.zip  # Extract files from a zip archive
  

7. Package Management

• apt (Debian/Ubuntu): Install, update, and manage packages.
  

   sudo apt update  # Update package list
   sudo apt install package_name  # Install a package
  

• yum (RHEL/CentOS): Similar to apt for Red Hat-based distributions.
  

   sudo yum install package_name  # Install a package
  

8. Automation and Scripting

• cron: Schedule periodic tasks.
  

   crontab -e  # Edit the cron jobs
  

• bash: Shell scripting.
  

   #!/bin/bash
   echo "Hello, World!"
  

9. Version Control (Git)

• git clone: Clone a repository.
  

   git clone https://github.com/user/repo.git  # Clone a git repository
  

• git pull: Update local repository with remote changes.
  

   git pull origin main  # Pull latest changes from the main branch
  

• git commit: Commit changes to the repository.
  

   git add .  # Stage all changes
   git commit -m "Commit message"  # Commit changes
  

10. Docker and Kubernetes

• docker ps: List running containers.
• docker images: List images.
• docker build: Build an image.
• kubectl get pods: List Kubernetes pods.
• kubectl apply -f: Apply a configuration file.

These commands cover the basics for managing a Linux environment, handling files, processes, networking, and working with popular DevOps tools like Git, Docker, and Kubernetes.