Installing Archlinux using ISO

Arch Linux is a lightweight and highly customizable Linux distribution. This guide covers the full installation process and details how to modify an existing Arch installation using the Arch Live ISO.

Part 1: Installing Arch Linux

Step 1: Boot into the Arch Linux ISO

Download the latest Arch Linux ISO from the official website.

https://archlinux.org/download/
Create a bootable USB using tools like dd , Rufus, ventoy (recommended), balenaEtcher:

if using dd dd if=archlinux.iso of=/dev/sdX bs=4M status=progress && sync
Boot from the USB and select “Arch Linux Installer”. (here is standard method)

Turn off your laptop completely.

Plug in your Arch USB stick.

Hit the power button and start spamming the end or F12 key (or your specific boot menu key) right away to open the boot options.

If F12 doesn’t work, some laptops use F2, F10, or Delete to enter the BIOS/Boot Menu

Choose your USB drive from the menu, and you’re ready to start the install!

Step 2: Connect to the Internet

For wired or ethernet connection:

ping -c 3 archlinux.org

For Wi-Fi: (use iwctl)

iwctl
device list ## wifi device name i.e wlan0 , and adapter i.e phy0
adapter phy0 set-property Powered on ## if powered off
station wlan0 scan ## scan wifi networks
station wlan0 get-networks ## lisiting of wifi networks
station wlan0 connect <SSID> ## connect to wifi network
station wlan0 show # to get info about wifi check state field
exit

dhcpcd # to get ip assigned

Verify with:

ip a
ping 1.1.1.1

Step 3: Update System Clock

timedatectl set-ntp true

Step 4: Partition the Disk

Check available disks

lsblk

Use fdisk or cfdisk (recommanded ) to partition:

In this Format

EFI Partition: 1GB (Type: EFI System) 
  
Root Partition: 400GB (Type: Linux Filesystem)
  
Swap Partition: 8GB (Type: Linux Swap)

EFI Partition size should be about 1 GB

Root Partition Size Should be at-least 20GB for smooth running

Swap Partition Size should be between 500MB to 8GB and its optional

We will use cfdisk here

cfdisk /dev/nvme0n1

use nvme0n1 or something that is system disk , dont use usb disk like sda

refer this guide for creating partition using cfdisk

/posts/tech/how-to-use-cfdisk

Step 5: Format and Mount Partitions

Always run in this sequence post-partitioning: EFI → Swap → Root, then mount

mkfs.fat -F32 /dev/nvme0n1p1   # EFI
mkswap /dev/nvme0n1p3          # Swap
mkfs.ext4 /dev/nvme0n1p2       # Root

now mount

mount /dev/nvme0n1p2 /mnt                  # Root
mount --mkdir /dev/nvme0n1p1 /mnt/boot/efi # EFI
swapon /dev/nvme0n1p3                      # Swap

Step 6: Install Base System

Update Key-ring if ISO is Old

pacman-key --init
pacman-key --populate archlinux
pacman -Sy archlinux-keyring
rm -rf /mnt/var/cache/pacman/pkg/* # Remove corrupted packages If Need

Update the mirrorlist change country if needed

--country India

reflector --country India --protocol https --latest 20 --sort rate \
  --save /etc/pacman.d/mirrorlist

Install packages (required)

pacstrap /mnt base linux linux-firmware nano sudo iwd reflector grub efibootmgr dhcpcd vim

Optional packages

pacstrap /mnt man-db man-pages less inetutils usbutils pciutils which diffutils file

Generate fstab:

genfstab -U /mnt >> /mnt/etc/fstab

Step 7: Chroot into the System

arch-chroot /mnt

Step 8: Configure System

Set Your time zone

example Asia/Kolkata

ln -sf /usr/share/zoneinfo/Asia/Kolkata /etc/localtime
hwclock --systohc

Edit Locale

based on Your laptop Keyboard and Language

common one is UTF-8 and United states English

nano /etc/locale.gen  # Uncomment en_US.UTF-8 UTF-8
locale-gen
echo "LANG=en_US.UTF-8" > /etc/locale.conf

Set Hostname

echo "archlinux" > /etc/hostname
nano /etc/hosts

Add The hosts

127.0.0.1   localhost
::1         localhost

Set The Root Password

passwd

add user if needed

useradd -m -G wheel -s /bin/bash username
passwd username

Give Sudo Permission (if needed)

nano /etc/sudoers # Uncomment "%wheel ALL=(ALL:ALL) ALL"

Install bootloader GRUB for UEFI

grub-install --target=x86_64-efi --efi-directory=/boot/efi --bootloader-id=GRUB
grub-mkconfig -o /boot/grub/grub.cfg

Exit arch-chroot , unmount and Reboot

exit
umount -R /mnt
reboot

Remove installation media and log in.

Part 2: Modifying an Existing Arch Linux Installation

Boot from your installation media and reach the command prompt.
Identify and mount your existing Arch Linux root partition to the /mnt directory.

⚠️ Warning: Do not format the partition. Simply mount it to access your files without erasing any data.
Enter the system by running arch-chroot /mnt.
Apply your changes, such as running passwd [username] to reset a password.
Finalize the process: Type exit to leave the chroot, run umount -R /mnt to safely unmount your partitions, and then reboot.

thats it.