Linux Technical Interview QA with Practical Sessions

Linux System Administration: Essential Concepts & Interview Preparation

User & Group Management in Linux

Master fundamental Linux user administration with this comprehensive overview. Learn how to:

• Understand the /etc/passwd file: Explore the crucial fields and their significance in user account management.
• Create Users: Learn various methods for creating users, including specifying primary and secondary groups, and using commands beyond useradd.
• Home Directory Permissions: Understand default permissions for user home directories and how to manage them effectively.
• .bash_profile vs .bashrc: Differentiate between these essential shell configuration files.
• User Creation with Customization: Utilize commands to define user UID, shell, and home directory during creation.
• Group Management: Modify a user's primary group and understand default group memberships (e.g., root).
• Deleting Users & Home Directories: Learn the implications of user deletion and how to securely remove home directories.
• Automatic Home Directory Files: Identify commonly created files within a user's home directory upon creation.
• User Session Monitoring: View currently logged-in users and their details using command-line tools.
• User Account Expiration: Set and view user account expiry dates.
• finger Command: Extract detailed information about a user using the finger command.
• Granting Root Privileges: Understand how to grant normal users root-level privileges safely.
• sudo Access: Configure sudo access for users without requiring a password for every command.
• visudo Security: Why use visudo instead of directly editing system files?
• File & Directory Permissions: Understand default permissions and their implications.
• Login/Logout Tracking: View user login and logout details for auditing and security.
• Group Membership: Check a user's primary and secondary group affiliations.
• Locking & Unlocking Accounts: Securely lock and unlock user accounts.

Linux Permissions: SUID, SGID, Sticky Bit & More

Deep dive into Linux file permissions and access control:

• SUID, SGID, & Sticky Bit: Understand the purpose and functionality of these special permission flags.
• umask Explained: Learn how umask controls default file and directory permissions.
• umask Default & Definition: Where is the default umask value defined and how does it work?
• Read-Only Directories: Can you cd into a directory with only read permissions?
• chmod -R: Understand the recursive application of chmod for modifying permissions.
• Restricting Access: How to prevent both normal and root users from modifying or deleting files.
• Sticky Bit Nuances: The difference between lowercase 't' and uppercase 'T' in sticky bit application.
• Soft vs. Hard Links: Explore the key differences between soft and hard links.
• umask vs. ulimit: Distinguish between these two important permission-related settings.

LVM (Logical Volume Management) in Linux

Gain expertise in managing storage with LVM:

• Volume Group Limits: How many volume groups can be created in a Linux system?
• Dynamic Volume Resizing: Can logical volumes be increased or decreased on the fly?
• Logical Volume Expansion: Learn how to increase the size of a logical volume.
• Logical Volume Reduction: Understand how to reduce the size of a logical volume.
• Scanning for LUNs: How to scan new LUNs or disks for LVM physical volumes.
• Scanning Existing Volume Groups: How to scan disks for existing volume groups.
• Scanning Logical Volumes: How to scan a logical volume from an existing volume group.
• Logical Volume Operations: How to stop, activate, and deactivate logical volumes and volume groups.
• Mirroring & RAID: Identify disks used for logical volume mirroring.
• Importing & Listing Volume Groups: List imported volume groups and available logical volumes.
• Detailed Volume Group Information: How to view comprehensive information about volume groups.

Linux Boot Process & Rescue Mode

Understand the Linux boot process and troubleshooting techniques:

• Boot Process Overview: A detailed explanation of the Linux boot sequence.
• BIOS & MBR: Define BIOS and MBR and their roles in the boot process.
• GRUB & GRUB2: Explain GRUB and its evolution