100+ Linux Administrator Interview Questions and Answers

File system integrity can be checked using fsck command in Linux.

• Use fsck command to check and repair file system errors

• Run fsck on unmounted file systems for accurate results

• Use options like -y to automatically repair errors without user intervention

Linux is an open-source operating system based on Unix. Unix is a family of multitasking, multiuser computer operating systems.

• Linux is open-source and free to use, while Unix is proprietary and usually requires a license.

• Linux has a larger community and more distributions (e.g. Ubuntu, CentOS), while Unix has fewer variations (e.g. Solaris, AIX).

• Linux is more customizable and can run on a wider range of hardware, while Unix is more stable and secure.

• Linux uses the GNU Genera...read more

The command to check load average is 'uptime' or 'w' in the terminal.

• Use the 'uptime' command to display the load average for the system.

• Alternatively, you can use the 'w' command to see load average along with other information.

• Load average represents the average system load over a period of time.

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

LVM (Logical Volume Manager) allows flexible disk management, enabling resizing of file systems and logical volumes dynamically.

• LVM provides abstraction over physical storage, allowing for easier management of disk space.

• To increase a file system size: Use 'lvextend' to increase the logical volume, then resize the file system with 'resize2fs'.

• Example to increase: 'lvextend -L +10G /dev/vg_name/lv_name' followed by 'resize2fs /dev/vg_name/lv_name'.

• To decrease a file system siz...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

The command to check the current directory in Linux is 'pwd', which stands for 'print working directory'.

• The 'pwd' command displays the full path of the current working directory.

• Example: Running 'pwd' in the terminal might output '/home/user'.

• It is useful for confirming your location in the filesystem.

• The command does not take any arguments or options.

To check memory space, use 'free' or 'top' command. LVM is Logical Volume Manager for managing disk space. Crontab is a tool for scheduling tasks. Swap memory is virtual memory used when physical memory is full.

• Check memory space using 'free' command to see total, used, and free memory

• LVM is a tool for managing disk space by creating logical volumes from physical volumes

• Crontab is a file used to schedule tasks to run at specific times

• To extend LVM, use 'lvextend' command to i...read more

Booting a computer involves several steps from power-on to loading the operating system.

• Power-On Self Test (POST): Checks hardware components like RAM and CPU.

• Bootloader: Loads the operating system from disk; examples include GRUB and LILO.

• Kernel Initialization: The OS kernel is loaded into memory and initialized.

• System Initialization: Services and processes are started, preparing the system for user interaction.

• User Login: The system prompts for user credentials to access th...read more

Steps for file system creation involve partitioning, formatting, and mounting the file system.

• Partition the disk using tools like fdisk or parted

• Format the partition with a file system like ext4 or xfs

• Create a mount point directory

• Mount the file system to the mount point

• Update /etc/fstab to automatically mount the file system on boot

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

LUN stands for Logical Unit Number, used to represent a logical volume on a storage area network (SAN).

• LUNs are virtual disks created on a SAN storage system.

• To extend a LUN, you can use tools like LVM (Logical Volume Manager) to add more physical storage to the existing LUN.

• To reduce a LUN, you can shrink the filesystem on the LUN and then shrink the LUN itself using storage management tools.

Linux is an open-source operating system based on Unix. Its components include kernel, shell, GUI, utilities, and applications.

• Kernel: manages hardware resources and provides services to other system components

• Shell: provides a command-line interface for users to interact with the system

• GUI: provides a graphical interface for users to interact with the system

• Utilities: perform various system tasks such as file management, networking, and security

• Applications: software program...read more

To check running processes and disk space, use commands like ps, top, df, and du.

• Use 'ps' command to display currently running processes

• Use 'top' command to display real-time system information, including processes

• Use 'df' command to check disk space usage on filesystems

• Use 'du' command to check disk usage of directories

LVM stands for Logical Volume Manager, used to manage disk space by creating logical volumes from physical volumes.

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

• To extend an LVM, first add a new physical volume to the volume group using 'pvcreate'.

• Then extend the volume group to include the new physical volume using 'vgextend'.

• Finally, extend the logical volume using 'lvextend' and resize the filesystem using 'resize2fs' or 'xfs_growfs'.

The Linux login process involves user authentication, session management, and shell initialization.

• 1. User initiates login via a terminal or graphical interface.

• 2. The system prompts for a username and password.

• 3. The login manager (e.g., getty, GDM) verifies credentials against /etc/passwd and /etc/shadow.

• 4. Upon successful authentication, the user's environment is set up (e.g., loading .bashrc).

• 5. The user is granted access to a shell or desktop environment.

Basic Linux commands are essential for navigating and managing the system effectively.

• ls: Lists files and directories in the current directory. Example: 'ls -l' for detailed listing.

• cd: Changes the current directory. Example: 'cd /home/user' to navigate to the user's home directory.

• cp: Copies files or directories. Example: 'cp file.txt /backup/' to copy 'file.txt' to the backup directory.

• mv: Moves or renames files or directories. Example: 'mv oldname.txt newname.txt' to renam...read more

If kernel stuck in update, we can try to reboot the system and check for any errors.

• Try to reboot the system

• Check for any errors

• If the issue persists, try to boot into a previous kernel version

• If all else fails, reinstall the kernel

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

To roll back updates, identify the update and use the appropriate command to remove it.

• Identify the update that needs to be rolled back

• Use the appropriate command to remove the update

• Verify that the rollback was successful

Apache is a popular open-source web server software. It is used to host websites and web applications.

• Apache is used to serve web content over the internet.

• To install Apache on Linux, you can use package managers like apt or yum.

• The default port number for Apache is 80, but it can be changed in the configuration file.

• Example: sudo apt-get install apache2

Rollback patching is a process of reverting a patch or update to a previous version.

• Rollback patching is useful when a patch or update causes issues or conflicts with the system.

• It involves undoing the changes made by the patch or update and restoring the system to its previous state.

• Rollback patching can be done manually or automatically depending on the system and the patching process.

• Examples of rollback patching tools include Windows System Restore and Linux's yum history...read more

I gained knowledge about the Linux field through formal education, hands-on experience, online resources, and continuous learning.

• Studied Linux operating system in college courses

• Worked on Linux servers in previous job roles

• Participated in online forums and communities like Stack Overflow for troubleshooting

• Read books and online tutorials on Linux administration

• Attended workshops and training sessions on Linux technologies

NFS stands for Network File System. It is a protocol used for sharing files/folders between Unix/Linux systems over a network.

• NFS allows a user on a client computer to access files over a network as if they were on the local hard drive.

• The NFS configuration file is /etc/exports, which lists the directories that can be exported to remote systems.

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

• NFS can be used to share files between Linux/Unix s...read more

LVM (Logical Volume Manager) is a tool used to manage disk storage in Linux systems. It allows for dynamic resizing of partitions.

• LVM allows for creating logical volumes from physical volumes

• To extend an LVM partition, first add a new physical volume to the volume group

• Then extend the logical volume using the 'lvextend' command

• Finally, resize the file system using 'resize2fs' or 'xfs_growfs'

DHCP stands for Dynamic Host Configuration Protocol. It is a network protocol that automatically assigns IP addresses to devices on a network.

• DHCP server assigns IP addresses to devices on a network

• It also provides other network configuration information such as subnet mask and default gateway

• DHCP uses a lease mechanism to manage IP address assignments

• DHCP operates on the client-server model

• Example: When a device connects to a network, it sends a DHCP request to the DHCP serv...read more