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Preparing for a Linux interview? Here’s a comprehensive list of 100+ Linux interview questions covering essential topics like commands, user management, security, and more. Whether you’re aiming for a DevOps, SysAdmin, or Software Engineering role, mastering these concepts will give you an edge.
You Should Know:
1. Basic Linux Commands
<h1>File & Directory Operations</h1> ls -lha # List files with details mkdir -p dir1/dir2 # Create nested directories rm -rf dir/ # Force delete a directory find / -name "*.log" # Find files by name <h1>Process Management</h1> ps aux | grep nginx # Check running processes kill -9 PID # Force kill a process top # Monitor system processes <h1>Networking</h1> ifconfig # Network interface details netstat -tuln # List open ports ping google.com # Check connectivity
#### **2. User & Permission Management**
<h1>User Operations</h1> useradd -m john # Create a user with home dir passwd john # Set user password usermod -aG sudo john # Add user to sudo group <h1>Permissions</h1> chmod 755 script.sh # Set read/write/execute chown user:group file # Change ownership
#### **3. Security & Hardening**
<h1>SSH Security</h1> ssh-keygen -t rsa # Generate SSH keys nano ~/.ssh/config # Configure SSH client <h1>Firewall (UFW)</h1> ufw allow 22/tcp # Allow SSH ufw enable # Enable firewall <h1>Log Monitoring</h1> tail -f /var/log/auth.log # Monitor auth attempts
#### **4. System & Performance**
<h1>Disk Usage</h1> df -h # Check disk space du -sh /var/log # Directory size <h1>Cron Jobs</h1> crontab -e # Edit cron jobs */5 * * * * /path/script.sh # Run every 5 mins
#### **5. Shell Scripting**
#!/bin/bash <h1>Backup script</h1> tar -czvf backup.tar.gz /path/to/files scp backup.tar.gz user@remote:/backup/
### **What Undercode Say:**
Linux interviews test practical knowledge—focus on commands, scripting, and troubleshooting. Practice these:
– grep, awk, sed for text processing.
– systemctl for service management.
– lsof to check open files.
– rsync for efficient file transfers.
– journalctl for system logs.
For advanced roles, study Kernel modules, SELinux, and Docker commands.
### **Expected Output:**
<h1>Example: Check active services</h1> systemctl list-units --type=service --state=running <h1>Example: Secure SSH (disable root login)</h1> sudo sed -i 's/PermitRootLogin yes/PermitRootLogin no/g' /etc/ssh/sshd_config sudo systemctl restart sshd
Master these, and you’ll ace your Linux interview! 🚀
References:
Reported By: S Wakhare – Hackers Feeds
Extra Hub: Undercode MoN
Basic Verification: Pass ✅
