Abhishek Srivastav

  User and Group Management in Linux Managing Local Users: Commands : adduser / useradd : Create new users. usermod : Modify existing user accounts. userdel : Delete users. Managing Local Groups: Primary and Supplementary Groups : Each user has a primary group and can belong to multiple supplementary groups. Commands : groupadd : Create new groups. groupmod : Modify existing groups. groupdel : Delete groups. Querying User Accounts: Commands : whoami : Displays the current logged-in user's name. who : Lists users currently logged in and their login details. w : Shows what users are currently doing. pinky : A lightweight version of finger , provides user information. last : Shows a history of user logins. id username : Displays user identity information. Managing Group Password Files: Password File : Located in /etc/shadow , requires root access to edit. Commands : sudo vipw / sudo vipw -s : Safely edit the password file. vigr : Edit group file. User & Group Quotas: Quota Manag...

  Understanding Partitioning: GPT vs. MBR GPT (GUID Partition Table): Protective MBR : GPT disks include a protective MBR to ensure compatibility with older systems. Data Integrity : GPT scatters copies of its partition table across the disk to prevent data loss in case of corruption. Unlimited Disk Space : Supports disks larger than 2TB. MBR (Master Boot Record): Limited Disk Space : Only supports disks up to 2TB. Partition Information : The MBR holds details about how the disk is partitioned. Linux File System Basics File System Mount Points: Root Directory : / Second Drive : /mnt Remote NFS/Samba : /home/ USB Drive : /media/ Virtual Environment : /proc , /sys Creating Partitions: Tools : lsblk : Displays the partition tree. cat /proc/partitions : Shows partition details. parted / gparted : GUI ( gparted ) and CLI ( parted ) tools for partition management. fdisk : CLI tool for managing partitions, with m for help. Formatting and Mounting File Systems File System Types : Linux : ...

  Understanding BIOS/UEFI and Boot Loaders BIOS vs. UEFI: BIOS : The Basic Input Output System, the traditional firmware interface for booting a computer. UEFI : The Unified Extensible Firmware Interface, a modern replacement for BIOS with enhanced features and security. GRUB/GRUB2: GRUB : The Grand Unified Bootloader, responsible for loading the kernel and initiating the boot process. GRUB2 : An updated version of GRUB, offering more features and flexibility. The Linux Boot Process BIOS/UEFI Initialization : First step in booting, initializing hardware and finding the bootloader. GRUB/GRUB2 : Loads the kernel, either vmlinux or vmlinuz , and passes control to it. Kernel Initialization : Kernel is loaded along with initrd (initial RAM disk), which contains necessary drivers and modules for accessing the file system. Kernel Panic : If an issue arises, Linux keeps the previous kernel as a fallback. Causes can include updates or hardware failures. Managing Linux Boot Modules Loading...