1. What is the difference between a hard link and a symbolic link in Linux?

2. How do you find the size of a directory and its contents?

3. Explain the use of the rsync command.

4. How do you set up a cron job to run a script every day at midnight?

5. What is the purpose of the /etc/fstab file?

6. How do you mount and unmount a filesystem?

7. Describe the process of partitioning a hard drive in Linux.

8. What is the lsof command used for?

9. How do you change the default shell for a user?

10. What are runlevels in Linux, and how do you change them?

11. Explain the difference between init and systemd.

12. How do you create and manage user groups?

13. What is the purpose of the /etc/passwd file?

14. How do you change file ownership and permissions using chown and chmod?

15. How do you check disk usage by files and directories?

16. What is the purpose of the /etc/shadow file?

17. How do you compress and decompress files using gzip and bzip2?

18. Explain how to use the awk command for text processing.

19. How do you monitor system performance using top and htop?

20. What is the iptables command used for?

21. How do you set up a basic firewall using ufw?

22. Explain the purpose of the /var/log directory.

23. How do you view and analyze log files?

24. What is the journalctl command used for?

25. How do you configure network interfaces using ifconfig or ip?

26. How do you set up a static IP address on a Linux system?

27. What is the netstat command used for?

28. How do you find and kill a process using its PID?

29. Explain how to use the grep command to search for text within files.

30. How do you schedule tasks using at and batch commands?

31. What is the purpose of the /proc directory?

32. How do you check memory usage using free and vmstat?

33. How do you create a disk partition using fdisk or parted?

34. What is the df command used for?

35. How do you extend or shrink a logical volume in LVM?

36. Explain the use of the tar command for archiving files.

37. How do you use the scp command to transfer files securely?

38. What is the ssh-keygen command used for?

39. How do you set up passwordless SSH login?

40. Explain the purpose of the sudoers file.

41. How do you add a user to the sudoers file?

42. What is the strace command used for?

43. How do you compile and install software from source?

44. Explain how to use the find command to search for files.

45. How do you set file permissions using symbolic and numeric modes?

46. What is SELinux, and how do you configure it?

47. How do you check the status of SELinux on your system?

48. Explain the purpose of the passwd command.

49. How do you change the default runlevel on a system using systemd?

50. What is the cron.d directory used for, and how do you use it?