linux

Question 1

What command displays the current working directory?

Answer 1

The command pwd displays the current working directory.

Question 2

How do you list all files, including hidden files, in a directory?

Answer 2

The ls -a command lists all files, including hidden ones.

Question 3

How can you view the contents of a file one screen at a time?

Answer 3

Use the less or more command to view file contents one screen at a time.

Question 4

What command is used to change file permissions?

Answer 4

The chmod command changes file permissions.

Question 5

How do you change ownership of a file in Linux?

Answer 5

Use the chown command to change file ownership.

Question 6

How can you check the permissions of a file?

Answer 6

The ls -l command displays the file permissions in detail.

Question 7

What is the difference between su and sudo?

Answer 7

su switches to another user, often root, requiring that user’s password. sudo runs a command with root privileges using the current user’s password.

Question 8

How do you display the first few lines of a file?

Answer 8

The head command displays the first few lines of a file.

Question 9

How do you search for a specific text string in files?

Answer 9

Use the grep command to search for a text string in files.

Question 10

What command would you use to display active processes?

Answer 10

The ps command displays active processes, or top for an interactive view of running processes.

Question 11

What is the purpose of the kill command?

Answer 11

The kill command is used to terminate a process by its PID (Process ID).

Question 12

How can you view system memory usage?

Answer 12

Use the free command or top to view system memory usage.

Question 13

What is the difference between hard and soft links?

Answer 13

A hard link points directly to the file’s data on disk, while a soft link (symbolic link) is a reference to another file’s path.

Question 14

What command shows the disk usage of a directory and its contents?

Answer 14

The du command shows the disk usage of a directory and its contents.

Question 15

How do you display the IP address of the machine?

Answer 15

Use the ip addr or ifconfig command to display the IP address.

Question 16

What is the purpose of the /etc/hosts file?

Answer 16

The /etc/hosts file maps hostnames to IP addresses for local name resolution.

Question 17

What command is used to download files from the internet?

Answer 17

The wget or curl command is used to download files from the internet.

Question 18

What is the cron daemon used for?

Answer 18

The cron daemon is used to schedule recurring tasks at specified intervals.

Question 19

How do you display the last 10 lines of a log file?

Answer 19

The tail command shows the last 10 lines of a file, or tail -f for real-time updates.

Question 20

How do you check the status of all services on a Linux system?

Answer 20

Use systemctl list-units --type=service to check the status of all services.

Question 21

What is virtualization?

Answer 21

Virtualization is the process of creating virtual instances of computer resources, such as servers, storage, and networks.

Question 22

What is the difference between a virtual machine and a container?

Answer 22

A virtual machine is a full operating system environment running on a hypervisor, while a container shares the host OS kernel and runs in isolated processes.

Question 23

What is a hypervisor?

Answer 23

A hypervisor is software that allows multiple virtual machines to run on a single physical host, with each VM isolated from others.

Question 24

How do Type 1 and Type 2 hypervisors differ?

Answer 24

Type 1 hypervisors run directly on hardware (bare-metal), while Type 2 hypervisors run on top of an existing operating system.

Question 25

What are some popular hypervisors used in the industry?

Answer 25

Popular hypervisors include VMware ESXi, Microsoft Hyper-V, and open-source solutions like KVM and Xen.

Question 26

What are the advantages of using containers over VMs?

Answer 26

Containers are lightweight, have lower overhead, and start faster than VMs since they share the host OS kernel.

Question 27

What is Docker, and why is it important in DevOps?

Answer 27

Docker is a platform for developing, shipping, and running applications in containers, making it easier to ensure consistency across development, testing, and production environments.

Question 28

How can you create a Docker container?

Answer 28

Use the `docker run` command with an image name to create and start a container, for example, `docker run ubuntu`.

Question 29

How do you list all running Docker containers?

Answer 29

The `docker ps` command lists all running containers.

Question 30

What is a Docker image?

Answer 30

A Docker image is a lightweight, standalone, executable package that includes everything needed to run a piece of software, including code, runtime, libraries, and system tools.

Question 31

What command allows you to access the shell of a running Docker container?

Answer 31

The `docker exec -it /bin/bash` command allows you to access the shell of a running container.

Question 32

How can you view resource usage by processes in real-time?

Answer 32

The `top` command shows real-time resource usage, including CPU, memory, and processes.

Question 33

How do you find the process ID (PID) of a specific process?

Answer 33

Use the `ps aux | grep ` command to find the PID of a process.

Question 34

What is the purpose of SSH?

Answer 34

SSH (Secure Shell) is a protocol for securely logging into and managing remote servers.

Question 35

How do you connect to a remote server using SSH?

Answer 35

Use the command `ssh user@host` to connect to a remote server.

Question 36

How can you copy files between two servers securely?

Answer 36

Use the `scp` (secure copy) command to transfer files between servers.

Question 37

What is a firewall, and how is it used in Linux?

Answer 37

A firewall controls incoming and outgoing network traffic based on security rules. In Linux, `iptables` or `firewalld` is used to configure firewall rules.

Question 38

How do you check which ports are listening on a server?

Answer 38

Use the `netstat -tuln` or `ss -tuln` command to see which ports are listening.

Question 39

How can you view system logs in Linux?

Answer 39

System logs are stored in the `/var/log` directory. You can use `tail`, `less`, or `cat` to view them.

Question 40

What is the purpose of environment variables in Linux?

Answer 40

Environment variables store information that can be used by applications and scripts to configure settings and paths.

Question 41

How can you view the value of an environment variable?

Answer 41

Use the `echo $VARIABLE_NAME` command to view an environment variable's value.

Question 42

How do you add a directory to the PATH environment variable?

Answer 42

Use `export PATH=$PATH:/new/directory/path` to add a directory to PATH.

Question 43

What is `sed` used for?

Answer 43

`sed` is a stream editor used to perform basic text transformations and replacements in files or streams.

Question 44

What is `awk` used for?

Answer 44

`awk` is a powerful text-processing tool for data extraction and reporting in structured text files.

Question 45

How do you monitor network traffic in Linux?

Answer 45

Use tools like `tcpdump` or `netstat` to monitor network traffic.