30+ Linux Administrator Interview Questions and Answers for Freshers

Files can be transferred from one server to another using tools like SCP, SFTP, or rsync.

• Use SCP (Secure Copy Protocol) to securely transfer files between servers. Example: scp file.txt user@server2:/path/to/directory

• Use SFTP (SSH File Transfer Protocol) for interactive file transfers. Example: sftp user@server2

• Use rsync for efficient synchronization of files between servers. Example: rsync -avz file.txt user@server2:/path/to/directory

Check for any processes or open files using the file system, then force unmount if necessary.

• Check for any processes or applications currently using the file system with 'lsof' command

• Kill any processes that are using the file system if necessary

• Try unmounting the file system again using 'umount -l' to force unmount if needed

Check disk visibility and partitioning to ensure proper filesystem expansion in Linux after assigning a disk from VMware.

• Verify if the disk is recognized by the OS using 'lsblk' or 'fdisk -l'.

• Check if the disk is partitioned using 'parted' or 'fdisk'. If not, create a partition.

• Use 'pvcreate' to initialize the disk for LVM if you're using logical volumes.

• If the disk is already partitioned, ensure the filesystem is resized using 'resize2fs' or similar commands.

• Reboot the VM if...read more

To get MAC based routing table, use 'ip neigh show' command. When pinging a server, kernel sends ICMP packets and updates ARP cache.

• Use 'ip neigh show' command to display MAC based routing table

• Kernel sends ICMP packets when pinging a server

• Kernel updates ARP cache with MAC address of the server

You can schedule a job regularly using cron jobs in Linux.

• Use the crontab command to edit the cron table

• Specify the schedule using the appropriate syntax (minute, hour, day of month, month, day of week)

• For example, to schedule a job to run every day at 3am, you would add the following line to the cron table: 0 3 * * * /path/to/command

Hard links and soft links are two types of links used in Unix-like operating systems to create shortcuts to files.

• Hard links are direct pointers to the inode of a file, while soft links are indirect pointers to the file name.

• Hard links cannot link directories or files on different filesystems, while soft links can.

• If the original file is deleted, hard links will still point to the data, while soft links will be broken.

• Example: 'ln file1 file2' creates a hard link, 'ln -s file...read more

Data upload can be done using Samba or FTP on a Linux system, with firewall protection.

• Data upload can be done using Samba, which is a file sharing protocol that allows users to access and share files over a network.

• FTP (File Transfer Protocol) is another method for data upload, allowing users to transfer files between a client and a server.

• Linux is an open-source operating system known for its stability, security, and flexibility.

• Firewall is a security system that monitors a...read more

NFS (Network File System) is a distributed file system protocol that allows a user on a client computer to access files over a network.

• NFS enables sharing of files and directories between multiple computers in a network.

• It provides transparent access to remote files as if they were local.

• NFS uses a client-server architecture where the server exports directories that can be mounted on client machines.

• It supports both read and write operations on shared files.

• NFS is commonly us...read more

sed command is used for text manipulation in Linux. Special permissions include setuid, setgid, and sticky bit.

• sed command is used for text substitution and manipulation in Linux

• Syntax: sed 's/pattern/replacement/g' filename

• Special permissions in Linux include setuid, setgid, and sticky bit

• Setuid: allows a user to execute a file with the permissions of the file owner

• Setgid: allows a user to execute a file with the permissions of the group owner

• Sticky bit: restricts the deleti...read more

NFS stands for Network File System, a distributed file system protocol that allows a user on a client computer to access files over a network.

• NFS allows a user to access files on a remote server as if they were local files.

• It is commonly used in Unix and Linux environments for sharing files and directories.

• NFS uses RPC (Remote Procedure Call) to communicate between the client and server.

• It provides centralized storage that can be accessed by multiple clients over a network.

• NF...read more

I harden my Linux server by implementing security measures to protect against potential threats.

• Regularly update the operating system and software to patch vulnerabilities

• Disable unnecessary services and ports to reduce attack surface

• Implement strong password policies and use SSH keys for authentication

• Set up a firewall to control incoming and outgoing traffic

• Monitor logs for suspicious activities and set up intrusion detection systems

The /mnt directory is used as a mount point for temporary mounting of filesystems, and fstab is a configuration file that lists filesystems to be mounted at boot.

• The /mnt directory is commonly used for temporarily mounting external storage devices or network shares.

• The fstab file is located at /etc/fstab and contains information about filesystems to be mounted at boot time.

• Entries in fstab include the device to mount, the mount point, filesystem type, mount options, and dump ...read more

Creating partitions in LVM involves initializing physical volumes, creating volume groups, and then creating logical volumes.

• 1. Install LVM tools: Use 'sudo apt install lvm2' on Debian-based systems.

• 2. Initialize physical volume: 'sudo pvcreate /dev/sdX' (replace sdX with your disk).

• 3. Create a volume group: 'sudo vgcreate myvg /dev/sdX'.

• 4. Create a logical volume: 'sudo lvcreate -n mylv -L 10G myvg'.

• 5. Format the logical volume: 'sudo mkfs.ext4 /dev/myvg/mylv'.

• 6. Mount the l...read more

LVM stands for Logical Volume Manager, a tool used to manage disk storage in Linux systems.

• LVM allows for dynamic resizing of logical volumes without downtime.

• It consists of physical volumes, volume groups, and logical volumes.

• Commands like pvcreate, vgcreate, lvcreate are used to create and manage LVM.

• LVM provides flexibility in managing storage space by allowing logical volumes to span multiple physical disks.

Cloud computing is the delivery of computing services over the internet, including servers, storage, databases, networking, software, and more.

• Cloud computing allows users to access and use resources on-demand without the need for physical infrastructure.

• It offers scalability, flexibility, cost-effectiveness, and increased efficiency.

• Examples of cloud computing services include Amazon Web Services (AWS), Microsoft Azure, and Google Cloud Platform.

Script to echo a line repeatedly

• Use a loop to echo the line multiple times

• Specify the number of times to repeat the line

• Example: for i in {1..5}; do echo 'Hello, World!'; done

To check WWN number, use commands like 'lsscsi' or 'lsblk' in Linux.

• Use 'lsscsi' command to list SCSI devices and their WWN numbers

• Use 'lsblk' command to list block devices and their WWN numbers

tcpdump is used for network troubleshooting and analysis by capturing and analyzing network packets.

• Captures network packets for analysis

• Helps in troubleshooting network issues

• Can be used to monitor network traffic

• Provides detailed information about network communication

• Useful for security analysis and monitoring

Code to print table of any number in Python

• Use a loop to iterate from 1 to 10 (for a 10x table)

• Multiply the number by the current iteration value

• Print the result for each iteration

JIT Compiler stands for Just-In-Time Compiler. It is a type of compiler that compiles code during runtime.

• JIT Compiler is used to improve the performance of applications by compiling code on the fly.

• It is commonly used in Java and .NET environments.

• JIT Compiler compiles code into machine code, which can be executed directly by the CPU.

• It can also optimize code by removing unnecessary instructions and reducing memory usage.

• Examples of JIT Compiler include HotSpot for Java and ...read more

The kernel is the core component of Linux, managing system resources and facilitating communication between hardware and software.

• Manages system resources like CPU, memory, and I/O devices.

• Acts as an intermediary between hardware and user applications.

• Handles process management, including scheduling and multitasking.

• Provides system calls for applications to interact with hardware.

• Ensures security and access control through user permissions.

To rollback a package, use package manager to uninstall current version and install previous version.

• Use package manager to uninstall current version of the package

• Install the previous version of the package using package manager

• Check for any dependencies that may need to be rolled back as well

To remove older kernels in Linux, use package management tools like apt or yum.

• Use 'apt autoremove' command in Debian-based systems to remove old kernels

• Use 'yum remove ' command in Red Hat-based systems to remove old kernels

• Check available kernels with 'uname -r' command before removing

To mount NFS, use the 'mount' command with the NFS server IP address and the mount point on the local machine.

• Use the 'mount' command followed by the NFS server IP address and the mount point on the local machine

• For example: sudo mount 192.168.1.100:/shared_folder /mnt/nfs_share

• Ensure that the NFS server is properly configured and accessible from the local machine

Workload in Linux refers to the amount of work being done by the system at a given time.

• Workload can include tasks such as running processes, handling network requests, and managing system resources.

• Monitoring workload is important for ensuring system performance and stability.

• Tools like top, htop, and sar can be used to track and analyze workload.

• High workload can lead to system slowdowns or crashes.

• Balancing workload across multiple servers can help improve overall system e...read more

Boot process is the sequence of steps that occur when a computer system is starting up.

• BIOS/UEFI initialization

• Loading the bootloader

• Loading the kernel

• Init process starts

• Launching user space processes

Patching involves applying updates to software to fix vulnerabilities and improve performance.

• Identify the software that needs to be patched

• Download the appropriate patches from the vendor's website

• Test the patches in a non-production environment before applying them to production systems

• Schedule downtime for applying patches to minimize disruption

• Document the patching process for future reference