🧪 Linux Proficiency Test – 3 Years Experience (90 Questions)

---

🔹 Section 1: Command Line Basics (10 questions)

1. What does the command pwd do?

2. How do you list all hidden files?

3. What is the output of echo $HOME?

4. How do you view the last 20 lines of a file?

5. Explain the difference between > and >>.

6. How can you check your current shell?

7. Which command will find the absolute path of an executable?

8. How do you display file sizes in a human-readable format with ls?

9. What does man do?

10. Write a command to find the number of .conf files in /etc.

---

🔹 Section 2: File and Directory Operations (10 questions)

11. How do you create a directory called projects?

12. What is the command to remove a directory and all its contents?

13. Explain how to use find to locate all .log files in /var/log.

14. How can you rename a file?

15. How do you move a file from one directory to another?

16. What does du -sh * do?

17. How can you compress a directory using tar and gzip?

18. What’s the command to extract a .tar.gz file?

19. Write a command to compare two text files.

20. How do you delete all .tmp files recursively?

---

🔹 Section 3: Permissions and Ownership (10 questions)

21. What does chmod 755 script.sh mean?

22. How do you make a script executable?

23. What command changes file ownership?

24. Explain the difference between chown and chgrp.

25. What is the output of ls -l?

26. What are SUID, SGID, and Sticky Bit?

27. How can you set default permissions using umask?

28. What is the command to view ACLs of a file?

29. How do you grant read and write permissions to the group only?

30. What does chmod o-rwx file.txt do?

---

🔹 Section 4: Process Management (10 questions)

31. How do you list all running processes?

32. What is the function of top and htop?

33. How do you kill a process by name?

34. What does ps aux | grep nginx show?

35. Explain zombie and orphan processes.

36. What does the nice value control?

37. How do you change the priority of a process?

38. What command pauses a running job?

39. How can you bring a background job to the foreground?

40. What’s the difference between &, nohup, and disown?

---

🔹 Section 5: Networking (10 questions)

41. What does ip a show?

42. How do you test if a server is reachable on port 80?

43. How do you display the routing table?

44. What is the command to download a file using the terminal?

45. How do you see your public IP address?

46. How do you open a port using iptables?

47. What does ss -tuln do?

48. What’s the difference between TCP and UDP?

49. How do you view active network interfaces?

50. What is the use of /etc/hosts?

---

🔹 Section 6: Package Management (10 questions)

51. What is the difference between apt and yum?

52. How do you update all installed packages on a Debian-based system?

53. How do you install a .deb file?

54. What does yum remove do?

55. How can you check which package provides a command?

56. What’s the command to list installed packages?

57. How do you upgrade a single package?

58. How can you add a PPA repository?

59. Explain the difference between dpkg and apt.

60. How do you remove unused dependencies?

---

🔹 Section 7: Users and Groups (10 questions)

61. How do you add a user?

62. What’s the command to change a user’s password?

63. How do you delete a user and their home directory?

64. How do you add a user to a group?

65. What’s the default shell for a new user?

66. How do you lock/unlock a user account?

67. What is stored in /etc/passwd?

68. How do you list all users on the system?

69. How can you change a user's shell?

70. What command shows a user’s group memberships?

---

🔹 Section 8: Shell Scripting and Automation (10 questions)

71. What is #!/bin/bash?

72. How do you pass arguments to a shell script?

73. What does $1, $2, $@ mean?

74. Write a script to display the current date and time.

75. How can you make a script run every hour?

76. What’s the difference between cron and at?

77. How do you debug a shell script?

78. What command schedules a cron job?

79. How do you redirect errors to a file?

80. Write a for loop to list numbers 1 to 10.

---

🔹 Section 9: System Monitoring & Logs (10 questions)

81. How do you check system load average?

82. Where are system logs stored?

83. What does journalctl do?

84. How do you watch real-time logs?

85. What command shows memory usage?

86. How do you check disk usage?

87. What tool can you use to monitor IO activity?

88. What is the use of uptime?

89. How do you track login attempts?

90. What is the purpose of /var/log/auth.log?

✅ Answer Key: Linux 90 Questions

🔹 Section 1: Command Line Basics

1. Prints current working directory

2. ls -a

3. Displays the path to the user's home directory

4. tail -n 20 filename

5. > overwrites, >> appends

6. echo $SHELL

7. which

8. ls -lh

9. Shows manual/help pages

10. find /etc -name "*.conf" | wc -l

---

🔹 Section 2: File and Directory Operations

11. mkdir projects

12. rm -rf directory_name

13. find /var/log -name "*.log"

14. mv oldname newname

15. mv file /new/location/

16. Shows size of each item in human-readable format

17. tar -czvf archive.tar.gz directory/

18. tar -xzvf archive.tar.gz

19. diff file1 file2

20. find . -name "*.tmp" -delete

---

🔹 Section 3: Permissions and Ownership

21. rwx for owner, rx for group, r for others

22. chmod +x script.sh

23. chown user:group filename

24. chown changes user & group, chgrp only group

25. Lists permissions, owner, group, size, etc.

26. Special permissions for exec, group files, and directories

27. Sets default permissions mask

28. getfacl filename

29. chmod g+rw filename

30. Removes all permissions from others

---

🔹 Section 4: Process Management

31. ps aux or top

32. Real-time process monitoring tools

33. pkill processname

34. Filters for processes named nginx

35. Zombie: finished but not reaped; Orphan: no parent

36. Process priority

37. renice

38. Ctrl + Z or kill -STOP pid

39. fg

40. & runs in background, nohup ignores hangups, disown removes job from shell

---

🔹 Section 5: Networking

41. Shows all IP addresses and interfaces

42. telnet host 80 or nc -zv host 80

43. ip route or route -n

44. wget or curl -O

45. curl ifconfig.me

46. iptables -A INPUT -p tcp --dport 80 -j ACCEPT

47. Shows listening ports and services

48. TCP = connection-based, UDP = connectionless

49. ip link show or ifconfig

50. Maps hostnames to IPs locally

---

🔹 Section 6: Package Management

51. Different package managers: apt = Debian, yum = RHEL

52. sudo apt update && sudo apt upgrade

53. sudo dpkg -i package.deb

54. Removes a package

55. dpkg -S /path/to/file or yum provides

56. dpkg -l or yum list installed

57. sudo apt install package-name

58. add-apt-repository ppa:name

59. dpkg is low-level, apt is higher-level

60. apt autoremove

---

🔹 Section 7: Users and Groups

61. adduser username or useradd

62. passwd username

63. userdel -r username

64. usermod -aG groupname username

65. Usually /bin/bash

66. passwd -l username / passwd -u username

67. Basic user info and UID/GID

68. cut -d: -f1 /etc/passwd

69. chsh -s /bin/zsh username

70. groups username

---

🔹 Section 8: Shell Scripting and Automation

71. Shebang – tells the shell to use Bash

72. ./script.sh arg1 arg2

73. $0 = script name, $1 = first arg, $@ = all args

74. echo "Today is $(date)"

75. Cron: 0 * * * * /path/to/script.sh

76. cron = recurring, at = one-time

77. bash -x script.sh

78. crontab -e

79. command 2> error.log

80. for i in {1..10}; do echo $i; done

---

🔹 Section 9: System Monitoring & Logs

81. uptime or top

82. /var/log

83. Views logs from systemd journal

84. tail -f /var/log/syslog

85. free -h

86. df -h

87. iotop or iostat

88. Shows uptime and load

89. last or who

90. Contains authentication logs