• ls : Lists files and directories in a specified directory.
• cd : Changes the current directory.
• mkdir : Creates a new directory.
• rmdir : Removes an empty directory.
• mv : Moves or renames files or directories.
• cp : Copies files or directories.
• rm : Deletes files or directories.
• find : Searches for files based on specific criteria.
• grep : Searches for text patterns within files.
• cat : Displays the contents of a file.
• head : Displays the first few lines of a file.
• tail : Displays the last few lines of a file.

Example:

# Create a new directory
mkdir my_project
# Move a file
mv my_file.txt my_project
# Find all files with .log extension
find . -name "*.log"
# Search for specific text in a file
grep "error" my_file.txt

• useradd : Creates a new user account.
• userdel : Deletes a user account.
• passwd : Changes a user's password.
• id : Displays the user and group IDs of a user.
• groupadd : Creates a new group.
• groupdel : Deletes a group.
• usermod : Modifies user account properties.
• groups : Lists the groups a user belongs to.

Example:

# Create a new user
useradd new_user
# Set password for the user
passwd new_user
# Add user to a group
usermod -G my_group new_user
# List groups the user belongs to
groups new_user

• ps : Lists currently running processes.
• kill : Sends a signal to a process.
• pkill : Kills processes by name or pattern.
• nohup : Runs a command without hanging up when the terminal session ends.
• bg : Puts a running process in the background.
• fg : Brings a background process back to the foreground.

Example:

# List all running processes
ps aux
# Kill a process with specific PID
kill 1234
# Kill all processes named "firefox"
pkill firefox

• ping : Checks network connectivity by sending ICMP echo requests.
• traceroute : Traces the path of network packets.
• nslookup : Performs DNS lookups.
• dig : Performs DNS lookups and displays detailed information.
• route : Displays and manipulates routing tables.
• ssh : Connects to remote systems securely using SSH.
• scp : Securely copies files between systems.

Example:

# Ping a website
ping google.com
# Trace the route to a server
traceroute 192.168.1.1
# Perform DNS lookup
nslookup google.com
# Connect to a remote server via SSH
ssh user@remote_server

• apt (Debian/Ubuntu): Manages software packages on Debian-based systems.
• yum (Red Hat/CentOS): Manages software packages on Red Hat-based systems.
• dnf (Fedora/CentOS): A modern package manager for Fedora and CentOS systems.
• pacman (Arch Linux): Package manager for Arch Linux.

Example:

# Update package lists
sudo apt update
# Install a package
sudo apt install nginx
# Remove a package
sudo apt remove nginx

• bash : The default shell on most Linux systems, providing scripting capabilities.
• zsh : An alternative shell known for its powerful features and customization options.
• python : A widely used scripting language for automation, system administration, and more.
• ruby : Another popular scripting language often used in DevOps.
• perl : A versatile scripting language suitable for system administration tasks.

Example:

#!/bin/bash

These commands are crucial for monitoring system health and troubleshooting issues:

• Monitoring resource usage: top , htop , df , free provide real-time insights into CPU, memory, and disk usage.
• Identifying performance bottlenecks: By analyzing process information and resource usage, you can pinpoint bottlenecks and optimize system performance.
• Network troubleshooting: ping , traceroute , netstat , and ifconfig help diagnose network connectivity issues.
• Logging and analysis: tail , grep , and awk can be used to analyze system logs to identify errors and understand system behavior.

Automation is a key principle in DevOps, and Linux scripting is essential:

• Automating repetitive tasks: Scripting simplifies tasks like backing up data, deploying applications, and restarting services.
• Creating deployment pipelines: Scripts can be used to orchestrate deployment processes, from code compilation to server deployment.
• Integrating with tools like Jenkins: Jenkins uses scripts to trigger build jobs, run tests, and deploy applications automatically.

Conclusion

Mastering Linux admin commands is fundamental for DevOps/cloud engineers. These commands empower you to efficiently manage servers, monitor system health, troubleshoot issues, and automate tasks. By utilizing these tools, you can streamline your workflows, enhance productivity, and ensure the smooth operation of your cloud infrastructure.

Here are some key takeaways:

• Practice regularly to become familiar with essential commands.
• Explore scripting languages like bash, Python, or Ruby for advanced automation.
• Embrace the power of tools like Ansible and Puppet for seamless server provisioning and configuration.
• Continuously learn new commands and techniques to stay ahead in the ever-evolving world of DevOps.