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Managing a Linux system efficiently requires mastering command-line tools. Below is a categorized list of essential Linux commands, along with practical examples and usage scenarios.
Package Management
– `apt-get` (Debian/Ubuntu):
sudo apt-get update Update package list sudo apt-get install nginx Install a package sudo apt-get remove nginx Remove a package
– `yum/dnf` (RHEL/CentOS/Fedora):
sudo yum install httpd Install a package sudo dnf remove httpd Remove a package
– `dpkg` (Debian low-level tool):
sudo dpkg -i package.deb Install a .deb file sudo dpkg -r package Remove a package
– `rpm` (Red Hat low-level tool):
sudo rpm -ivh package.rpm Install an RPM sudo rpm -e package Remove a package
Networking Commands
– `ifconfig` (Legacy, use `ip` now):
ifconfig eth0 up Enable network interface ifconfig eth0 down Disable interface
– `ping` (Check connectivity):
ping google.com Continuous ping ping -c 4 google.com Ping 4 times
– `netstat` (Network stats):
netstat -tuln List listening ports netstat -r Display routing table
– `iptables` (Firewall rules):
sudo iptables -L List firewall rules sudo iptables -A INPUT -p tcp --dport 22 -j ACCEPT Allow SSH
Process Management
– `ps` (Process snapshot):
ps aux List all running processes ps -ef | grep nginx Find a specific process
– `top` (Real-time process monitor):
top Interactive process viewer
– `kill` (Terminate processes):
kill -9 PID Force kill a process killall nginx Kill all nginx processes
System & Service Control
– `systemctl` (Systemd services):
sudo systemctl start nginx Start a service sudo systemctl enable nginx Enable on boot sudo systemctl status nginx Check service status
– `service` (Legacy service management):
sudo service apache2 restart Restart a service
– `chkconfig` (Legacy runlevel control):
sudo chkconfig httpd on Enable service at boot
File & Directory Operations
– `ls` (List files):
ls -la Show all files (including hidden)
– `chmod` (Change permissions):
chmod 755 script.sh Give execute permissions chmod +x script.sh Make file executable
– `chown` (Change ownership):
sudo chown user:group file.txt Change owner & group
– `grep` (Search text):
grep "error" /var/log/syslog Find errors in logs
User & Group Management
– `useradd` (Create user):
sudo useradd -m newuser Create user with home dir
– `usermod` (Modify user):
sudo usermod -aG sudo newuser Add user to sudo group
– `passwd` (Change password):
sudo passwd newuser Set user password
Disk & Memory Management
– `df` (Disk space):
df -h Human-readable disk usage
– `free` (Memory usage):
free -m Show memory in MB
You Should Know:
– `awk` (Advanced text processing):
awk '{print $1}' file.txt Print first column
– `sed` (Stream editing):
sed 's/old/new/g' file.txt Replace text globally
– `cron` (Schedule tasks):
crontab -e Edit cron jobs
What Undercode Say:
Mastering these Linux commands enhances system administration efficiency. Automate tasks, debug issues, and secure systems using these essential tools.
Expected Output:
A structured, actionable Linux command cheatsheet with real-world usage examples.
Prediction:
As Linux remains dominant in servers and cloud environments, proficiency in CLI tools will continue to be a critical skill for IT professionals.
References:
Reported By: Parasmayur Linux – Hackers Feeds
Extra Hub: Undercode MoN
Basic Verification: Pass ✅
