Run Arch-Linux from a Flash Drive

Many users have a single operating system installed at their laptops and they don't want to risk loosing their job by installing a second operating system (especially these users that rely on one single internal hard drive).
So here is a way to install a popular linux distribution called arch-linux , on a usb flash drive.

The complete guide for arch linux beginners is located here : Beginners' Guide

This guide is great but here what you should do to run arch-linux completely from an external flash drive.
The operating system that I am running for this example is windows 8.

1.First we create an arch-linux live cd from this link : https://www.archlinux.org/download/
2.Boot using live cd, and you are automatically logged in as root
3.Check with

lsblk

that the USB device is not mounted.
At this stage you should probably see your system internal hdd as sda and your external flash drive as sdb.
4. run

cfdisk /dev/sdb

The example system will contain a 15 GB root partition, and a home partition for the remaining space.

It should be emphasized that partitioning is a personal choice and that this example is only for illustrative purposes. See Partitioning.

Root:

Choose New (or press N) - Enter for Primary - type in "15360" - Enter for Beginning - Enter for Bootable.

Home:

• Press the down arrow to move to the free space area.
• Choose New (or press N) - Enter for Primary - Enter to use the rest of the drive (or you could type in the desired size).

Here's how it should look like:

Name    Flags     Part Type    FS Type          [Label]       Size (MB)
-----------------------------------------------------------------------
sda1    Boot       Primary     Linux                             15360
sda2               Primary     Linux                             133000*

Double check and make sure that you are happy with the partition sizes as well as the partition table layout before continuing.

If you would like to start over, you can simply select Quit (or press Q) to exit without saving changes and then restart cfdisk.

If you are satisfied, choose Write (or press Shift+W) to finalize and to write the partition table to the drive. Type "yes" and choose Quit (or press Q) to exit cfdisk without making any more changes.

5. run

mkfs.ext4 /dev/sdb1

mkfs.ext4 /dev/sdb2

Now both flash drive partitions are formated with the ext4 filesystem.

6. Follow the rest of the Beginners' Guide and pay attention to these parts :
i) Create an initial ram disk environment.
Study well this document ( Hooks) and add the usb word in the

/etc/mkinitcpio.conf

at the proper line.
ii) Install and configure a bootloader.
Grub is a good choice if you use windows, so use the Grub instructions here.
If you get any errors when trying to execute

grub-install --target=i386-pc --recheck /dev/sdb

you can try (like me) to add the following -force parameter like this

grub-install --target=i386-pc --recheck --debug --force /dev/sdb

iii) Add your windows operating system option when you boot from the flash drive by doing the following (with root privileges) :

pacman -S os-prober

to install the os-prober package and then run

grub-mkconfig -o /boot/grub/grub.cfg

to create the boot screen menu.

Now you have a complete operating system installed in your flash drive, without touching your system's internal hard drive!