Linux Interview Questions and Answers

Are you looking for Linux interview questions? Hope you are in the right place to get most of the entry-level interview questions. Below questions are framed for those who certified or not certified with minimum knowledge in Linux. The explanation for each question will be updated in the future with links refer to each answer.

Go through all the Linux Interview questions to make sure yourself prepared.

The commands start with the “#” symbol need to be run from a privileged superuser (admin) account. Starting with “$” commands can be run from any unprivileged accounts (Normal users).

Date/Time/Timezone/NTP Management

How will you print the Date & time in Linux?

$ date

2. Which daemon will handle time synchronization in Red Hat Linux 7, Centos 7, Oracle Linux 7?

chronyd

3. How will you set Date/time on a Red Hat 7/8, CentOS 7, Oracle Linux 7/8?

# timedatectl

4. Protocol / Port number used by NTP?

UDP / 123

5. What command used to list only the directories?

$ ls -d

6. How to find how long a server running?

$ uptime

Linux Permissions

7. How to change files mode permission in Linux?

# chmod

8. How to change ownership of a file in Linux?

# chown

9. What is SetUID, SetGID?

The setuid is a permission which allows the users to execute a program with the permissions of its owner. The setgid is a permission that allows the user to exec a program with the permissions of the group owner.

10. How to list and change the access control list of a file.

# getfacl file_name
# setfacl file_name

11. Explain what will chmod 640 file_name do?

Provide Read, Write access for the user, Read access for the group, no permission for others.

12. Set GID with any permission for /home/sysadmin/test.txt

# chmod 2774 /home/sysadmin/test.txt

13. What is the default permission for a file when created in Linux.

644

Note: This depends on umask.

Linux File Systems & Partitioning

14. How to create an ext4 filesystem

# mkfs.ext4 /dev/device_name
# mkfs -t ext4 /dev/device_name

15. What is the default file system of RHEL 7, Centos 7, Oracle Linux 7?

# xfs

16. Default home directory of root user will be under which location?

/root

17. How will you partition a disk in Linux?

# fdisk /dev/disk_name

Read more about how to partition using fdisk by click on FDISK to partition the disks in Linux

18. How to create a Logical Volume using Physical extends?

# lvcreate -l 43232 -n some_name vg_name

-l will be used to create using extends

For a deep understanding of how Logical volume management works refer to Create Logical volume management LVM file-system in Linux

19. How to remove volume group from a Linux server?

# vgremove vg_remove

20. What are the steps need to be followed to create a logical volume in Linux?

# fdisk /dev/disk_name
# pvcreate /dev/disk_name
# vgcreate name /dev/disk_name
# lvcreate -n lv_name vg_name

21. Which command used for creating swap?

# mkswap /dev/dev_name

22. How will you mount a file-system?

# mount /dev/dev_name /mount_point

Read more about Create and mount filesystems in Linux

23. Which command will list UUID of all block devices?

# blkid

24. How to activate and deactivate a swap?

# swapon /dev/device_name
# swapoff /dev/device_name

25. How to display total disk usage of the current directory?

$ du -sh

26. How to make a file system persistent during reboot?

Adding entry in FSTAB

27. The maximum number of  Primary Partitions can exist on one drive?

4

28. How to list the available mount points in Linux in human-readable format?

# df -hP

29. Which command used to list the available NFS exports from client machines.

# showmount -e server_IP

User Management

30. How to change the shell of a user?

# chsh -s /bin/bash user_name 

31. How to check the ageing of a User in Linux

# chage -l user_name

32. How to create a user with UID 5000

# useradd -u 5000 user_name

33. Which command can be used to modify user information?

# usermod

34. How to remove a user from Linux server?

# userdel user_name

35. Default UID of root user?

0

36. How to print user information’s UID, GID and Groups?

$ id user_name

37. How to remove a group from Linux servers.

# groupdel group_name

38. How to lock a user password

# passwd -l username

39. In which file, all recently entered commands will be stored?

.bash_history

Linux Networking

40. How to configure IP using TUI/CLI?

# nmtui
# nmcli

41. How to bring an interface up or down without restarting or affecting other interfaces?

# ifup ens33
# ifdown ens33

42. How to print the host-name in Linux with short and FQDN format?

# hostname -s
# hostname -f

43. How to set the hostname in RHEL 7 Linux?

# hostnamectl set-hostname some_name_here

44. Which command will print the gateway information in Linux?

# route -n
# netstat -nr
# ip route

45. The default location of the interface files will be under.

/etc/sysconfig/network-scripts/

46. Which file will show all Services, protocol and Port numbers in Linux?

$ cat /etc/services

Package & Repository Management

47. What is YUM? Abbreviation of “YUM”?

Yellowdog Update Manager or Modifier

Learn how to use YUM command for package management by referring to 31 Yum command for Package Management in Linux

48. How to list all installed package using rpm command.

# rpm -qa

49. Which package used for setting up an Apache webserver

httpd

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