As a Linux system administrator, the command line is your most powerful tool. Whether you’re managing users, monitoring performance, troubleshooting issues, or automating tasks, knowing the right commands can save you hours of work and headaches.

In this guide, we’ll cover 25 must-know Linux commands that every sysadmin should have in their toolkit — with examples and tips for practical usage.

🔧 1. top

View real-time system performance and processes.

top

Press q to quit. Use htop for a better interactive view (if installed).

🔧 2. ps

Display running processes.

ps aux | grep nginx

Useful for checking if a service is running.

🔧 3. df

Check disk usage.

df -h

The -h flag makes sizes human-readable.

🔧 4. du

Check file/folder size.

du -sh /var/log

Perfect for locating large directories.

🔧 5. free

Show system memory usage.

free -h

Helpful for troubleshooting memory issues.

🔧 6. uptime

Check how long the system has been running.

uptime

Also shows load averages.

🔧 7. who

See who is currently logged in.

who

Good for monitoring user sessions.

🔧 8. netstat

View network connections and ports.

netstat -tuln

Use ss on newer systems as a replacement.

🔧 9. ping

Test connectivity to another system.

ping google.com

Press Ctrl + C to stop.

🔧 10. traceroute

Trace the path packets take to a host.

traceroute linuxnugget.com

Useful for diagnosing network issues.

🔧 11. ifconfig / ip

View or configure network interfaces.

ip a

ifconfig is deprecated, use ip instead.

🔧 12. hostname

Display or set the system hostname.

hostnamectl set-hostname myserver

🔧 13. systemctl

Control system services.

systemctl restart sshd systemctl status nginx

🔧 14. journalctl

View logs managed by systemd.

journalctl -xe

Perfect for troubleshooting startup and service errors.

🔧 15. chmod

Change file or directory permissions.

chmod 755 script.sh

🔧 16. chown

Change file or directory ownership.

chown user:group file.txt

🔧 17. crontab

Schedule recurring tasks.

crontab -e

Example to run a backup every day at midnight:

0 0 * * * /usr/local/bin/backup.sh

🔧 18. rsync

Efficiently sync files/directories.

rsync -av /source /destination

Often used for backups or migrations.

🔧 19. scp

Securely copy files between systems.

scp file.txt user@server:/home/user/

🔧 20. tar

Archive and compress files.

tar -czvf archive.tar.gz /folder

Extract with:

tar -xzvf archive.tar.gz

🔧 21. grep

Search for patterns in files.

grep 'error' /var/log/syslog

🔧 22. find

Locate files based on name, size, date, etc.

find / -name "*.conf"

🔧 23. nano / vim

Edit files from the terminal.

nano /etc/hosts

Use vim if you’re comfortable with more powerful editing.

🔧 24. useradd, passwd, usermod, userdel

User management commands:

sudo useradd alice sudo passwd alice sudo usermod -aG sudo alice sudo userdel alice

🔧 25. reboot / shutdown

Reboot or shut down the system.

sudo reboot sudo shutdown now

✅ Final Thoughts

These 25 Linux commands are essentials for every sysadmin’s toolbox. Mastering them will make your work faster, more efficient, and more powerful.

Want to become a command-line ninja? Practice these commands daily, explore their flags, and use man pages to go deeper:

man rsync

About the Author
Richard Igwegbu is the founder of Unix Training Academy, and a seasoned Linux, Cloud, and DevOps professional. He’s dedicated to helping new and experienced sysadmins master real-world skills.

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