HCLTech Linux System Administrator Interview Questions and Answers

Patching physical servers involves identifying vulnerabilities, testing patches, scheduling downtime, and applying patches.

• Identify vulnerabilities through vulnerability scanning or manual review

• Test patches in a non-production environment to ensure compatibility and stability

• Schedule downtime with stakeholders and communicate the impact of the patching

• Apply patches using a patch management tool or manually

• Verify the s...read more

Patching rollback can be done by identifying the patch, uninstalling it, and restoring the previous version.

• Identify the patch that caused the issue

• Uninstall the patch using the appropriate command

• Restore the previous version of the software or package

• Test to ensure the issue has been resolved

RHEL7 is the newer version with improved features and security updates.

• RHEL7 has better support for Docker and containers

• RHEL7 has improved security features like firewalld and SELinux

• RHEL7 has updated versions of software packages

• RHEL7 has a new default file system, XFS

• RHEL7 has improved networking capabilities with NetworkManager

• RHEL6 is still widely used and has long-term support until 2024

LVM (Logical Volume Manager) is a disk management tool used in Linux systems to manage storage devices and create logical volumes.

• LVM allows for easy management of storage by abstracting physical storage devices into logical volumes.

• It provides features like volume resizing, snapshots, and striping for improved performance and flexibility.

• LVM enables dynamic allocation of storage space, making it easier to add or remov...read more

Patching is the process of applying updates or fixes to software or systems to address vulnerabilities or improve functionality.

• Patching involves downloading and installing updates provided by software vendors.

• It helps to fix bugs, security vulnerabilities, and improve performance.

• Patches can be applied to operating systems, applications, or firmware.

• Regular patching is crucial to maintain system integrity and protect ...read more

LVM (Logical Volume Manager) is configured by creating physical volumes, volume groups, and logical volumes.

• Create physical volumes using the 'pvcreate' command

• Create volume groups using the 'vgcreate' command

• Create logical volumes using the 'lvcreate' command

• Format the logical volumes with a file system using the 'mkfs' command

• Mount the logical volumes to desired mount points using the 'mount' command

• Update the '/etc/

Decommission is the process of retiring a system or service, while recommission is the process of bringing it back into service.

• Decommission involves shutting down and removing a system or service from operation.

• Recommission involves restoring a decommissioned system or service back into operation.

• Decommission and recommission are common processes in IT infrastructure management.

• Examples include retiring an old server ...read more

NFS allows remote access to files and directories, providing centralized storage and easy sharing.

• Enables sharing of files and directories across multiple systems

• Reduces storage costs by centralizing data on a single server

• Improves data availability and reliability through redundancy

• Simplifies administration by allowing for centralized management

• Examples: Sharing files between a web server and a database server, sharin

A user can be created in a single line command using the 'useradd' command in Linux.

• Use the 'useradd' command followed by the username to create a user.

• Specify additional options like home directory, shell, etc. if required.

• Example: useradd john -m -s /bin/bash

To reset the root password, you can use the single-user mode or a bootable Linux distribution.

• Boot into single-user mode by interrupting the boot process and appending 'init=/bin/bash' to the kernel command line.

• Remount the root filesystem as read-write using the 'mount -o remount,rw /' command.

• Change the root password using the 'passwd' command.

• Alternatively, boot from a bootable Linux distribution like a Live CD or U...read more

Possible causes of user not able to login to an application

• Incorrect username or password

• Account locked or disabled

• Expired password

• Network connectivity issues

• Application server down

• Incorrect permissions or access rights

• Firewall blocking access

• Authentication server issues

• Application configuration errors

To set the password for a newly created user in Linux, use the 'passwd' command followed by the username.

• Open the terminal or SSH into the Linux system

• Run the 'passwd' command followed by the username of the new user

• Enter and confirm the new password when prompted

A cron job is a scheduled task that runs automatically at specific intervals on a Linux system.

• Cron jobs are managed by the cron daemon, which reads a configuration file called crontab.

• To write a cron job, you need to edit the crontab file using the 'crontab' command.

• Each line in the crontab file represents a separate cron job and follows a specific format.

• The format consists of five fields: minute, hour, day of month,...read more

An I node number is a unique identifier assigned to each file in a Unix-like file system.

• I node number is also known as index node number.

• It contains metadata about the file such as ownership, permissions, timestamps, etc.

• It is used by the operating system to locate and access the file on the disk.

• The command 'ls -i' can be used to display the I node number of a file.