The Ultimate Linux Command Guide for DevOps Engineers (With Examples!)

As a DevOps engineer, mastering Linux commands is crucial for managing servers, automating deployments, troubleshooting issues, and handling infrastructure efficiently. This guide covers essential Linux commands that every DevOps engineer should know. Table of Contents File and Directory Management User and Permission Management Process Management Networking Commands Disk and Storage Management System Monitoring and Performance Tuning Package Management Logging and Troubleshooting Automation and Scheduling 1. File and Directory Management Print Working Directory pwd Displays the current working directory. List Files and Directories ls -lah -l: Long listing format. -a: Show hidden files. -h: Human-readable file sizes. Change Directory cd /path/to/directory Move into a specified directory. Create a Directory mkdir new_directory Creates a new directory. Create an Empty File touch filename Creates an empty file. Write to a File echo 'Hello, World!' > filename Writes 'Hello, World!' into a file (overwrites content). Append Text to a File echo 'New Line' >> filename Appends 'New Line' to an existing file. Open a File for Editing nano filename Opens the file in the nano text editor. Remove a File or Directory rm -rf file_or_directory -r: Remove directories and their contents. -f: Force delete without confirmation. Copy and Move Files cp source_file destination mv source_file destination cp: Copies a file or directory. mv: Moves (or renames) a file or directory. 2. User and Permission Management Check Current User whoami Displays the current logged-in user. Add a New User sudo useradd -m username -m: Creates a home directory for the user. Change File Permissions chmod 755 filename 7: Read, write, and execute for the owner. 5: Read and execute for group and others. Change File Ownership sudo chown user:group filename chown: Change ownership of a file or directory. 3. Process Management View Running Processes ps aux Displays all running processes. Kill a Process kill -9 process_id -9: Forcefully terminates a process. Monitor System in Real Time top Displays system resource usage. 4. Networking Commands Check Network Interfaces ip a Displays IP addresses and network interfaces. Test Connectivity ping google.com Sends ICMP echo requests to check connectivity. Check Open Ports netstat -tulnp Lists open ports and their associated processes. 5. Disk and Storage Management Check Disk Usage df -h Displays disk space usage in a human-readable format. Check Directory Size du -sh /path/to/directory -s: Summarizes the total size. -h: Human-readable format. 6. System Monitoring and Performance Tuning View System Uptime uptime Shows how long the system has been running. Check Memory Usage free -m Displays memory usage in megabytes. Monitor Logs in Real Time tail -f /var/log/syslog Displays live updates from a log file. 7. Package Management Install a Package (Debian-based) sudo apt install package_name Install a Package (Red Hat-based) sudo yum install package_name Remove a Package sudo apt remove package_name 8. Logging and Troubleshooting Check System Logs journalctl -xe Displays system logs with detailed errors. View Authentication Logs cat /var/log/auth.log Shows login attempts and authentication logs. 9. Automation and Scheduling Schedule a Cron Job crontab -e Opens the crontab file for scheduling tasks. Example Cron Job (Runs every day at 2 AM): 0 2 * * * /path/to/script.sh Conclusion Mastering these Linux commands will significantly improve your efficiency as a DevOps engineer. Whether managing servers, troubleshooting issues, or automating tasks, these commands form the foundation of your daily operations. Which command do you use the most? Let me know in the comments!

Mar 7, 2025 - 05:32

The Ultimate Linux Command Guide for DevOps Engineers (With Examples!)

As a DevOps engineer, mastering Linux commands is crucial for managing servers, automating deployments, troubleshooting issues, and handling infrastructure efficiently. This guide covers essential Linux commands that every DevOps engineer should know.

File and Directory Management
User and Permission Management
Process Management
Networking Commands
Disk and Storage Management
System Monitoring and Performance Tuning
Package Management
Logging and Troubleshooting
Automation and Scheduling

1. File and Directory Management

Print Working Directory

pwd

Displays the current working directory.

List Files and Directories

ls -lah

-l: Long listing format.
-a: Show hidden files.
-h: Human-readable file sizes.

Change Directory

cd /path/to/directory

Move into a specified directory.

Create a Directory

mkdir new_directory

Creates a new directory.

Create an Empty File

touch filename

Creates an empty file.

Write to a File

echo 'Hello, World!' > filename

Writes 'Hello, World!' into a file (overwrites content).

Append Text to a File

echo 'New Line' >> filename

Appends 'New Line' to an existing file.

Open a File for Editing

nano filename

Opens the file in the nano text editor.

Remove a File or Directory

rm -rf file_or_directory

-r: Remove directories and their contents.
-f: Force delete without confirmation.

Copy and Move Files

cp source_file destination
mv source_file destination

cp: Copies a file or directory.
mv: Moves (or renames) a file or directory.

2. User and Permission Management

Check Current User

whoami

Displays the current logged-in user.

Add a New User

sudo useradd -m username

-m: Creates a home directory for the user.

Change File Permissions

chmod 755 filename

7: Read, write, and execute for the owner.
5: Read and execute for group and others.

Change File Ownership

sudo chown user:group filename

chown: Change ownership of a file or directory.

3. Process Management

View Running Processes

ps aux

Displays all running processes.

Kill a Process

kill -9 process_id

-9: Forcefully terminates a process.

Monitor System in Real Time

top

Displays system resource usage.

4. Networking Commands

Check Network Interfaces

ip a

Displays IP addresses and network interfaces.

Test Connectivity

ping google.com

Sends ICMP echo requests to check connectivity.

Check Open Ports

netstat -tulnp

Lists open ports and their associated processes.

5. Disk and Storage Management

Check Disk Usage

df -h

Displays disk space usage in a human-readable format.

Check Directory Size

du -sh /path/to/directory

-s: Summarizes the total size.
-h: Human-readable format.

6. System Monitoring and Performance Tuning

View System Uptime

uptime

Shows how long the system has been running.

Check Memory Usage

free -m

Displays memory usage in megabytes.

Monitor Logs in Real Time

tail -f /var/log/syslog

Displays live updates from a log file.

7. Package Management

Install a Package (Debian-based)

sudo apt install package_name

Install a Package (Red Hat-based)

sudo yum install package_name

Remove a Package

sudo apt remove package_name

8. Logging and Troubleshooting

Check System Logs

journalctl -xe

Displays system logs with detailed errors.

View Authentication Logs

cat /var/log/auth.log

Shows login attempts and authentication logs.

9. Automation and Scheduling

Schedule a Cron Job

crontab -e

Opens the crontab file for scheduling tasks.

Example Cron Job (Runs every day at 2 AM):

0 2 * * * /path/to/script.sh

Conclusion

Mastering these Linux commands will significantly improve your efficiency as a DevOps engineer. Whether managing servers, troubleshooting issues, or automating tasks, these commands form the foundation of your daily operations.

Which command do you use the most? Let me know in the comments!