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This page explains how to install Arch Linux on a USB flash drive. The end
result is a persistent installation identical to that on a normal hard drive
along with several performance optimizations aimed at running Linux on removable
flash media.
The only packages explicitly installed besides
linux,
linux-firmware, and
base are:
- acpi
- efibootmgr
- grub
- iwd
- polkit
- sudo
- vim
Basic services, such as networking and time sync, are all handled by
systemd.
Prepare USB Stick
This bootable Linux USB stick will be compatible with both BIOS and UEFI
booting modes. In order for a storage device to boot in BIOS mode, the first
512 bytes of the device's memory must contain an
MBR
(master boot record). For a storage device to boot in UEFI mode, a special
EFI
system partion is required. Both partitions can be
created using
gdisk.
Before proceeding, determine the device name of the target USB
drive. View the currently available block devices before inserting the USB:
#
lsblk
Now insert the target flash drive and view the devices again.
The newly detected device /dev/sdX is the name of the target USB you
will use for further partitioning and formatting. Note that in the device name
you will use is literally /dev/sdX where the only thing that changes
is the single lowercase letter value of X. Double check that you have
the correct device name /dev/sdX, lest you may repartition the
internal hard drive of the machine you are on!
wipe
The process of zeroing out or wiping the target USB is almost
always optional. Overwriting the USB with zeros may be needed in rare cases
when previous data aligns with the newly created partition table. If you have
trouble installing a bootloader further on in the installation, you may have to
come back to this point and wipe your USB before continuing.
Use dd to write the USB with all zeros, permanently erasing all
data:
#
dd if=/dev/zero of=/dev/sdX status=progress
Expect this to take a relatively long time (hour+) depending on
the size of the USB.
partition
Use
sgdisk
to create a 10M BIOS partition, a 500M EFI partition, and
allocate the rest of the USB to a Linux partition:
#
sgdisk -o -n 1:0:+10M -t 1:EF02 -n 2:0:+500M -t 2:EF00 -n 3:0:0 -t 3:8300 /dev/sdX
View the new block layout of the target USB device:
#
lsblk
/dev/sdX
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINTS
sdX 8:112 1 14.5G 0 disk
├─sdX1 8:113 1 10M 0 part
├─sdX2 8:114 1 500M 0 part
└─sdX3 8:115 1 14G 0 part
You should now have three blocks on your target USB device: a 10MB block
/dev/sdX1, a 500MB block
/dev/sdX2, and a block for all the
remaining memory
/dev/sdX3.
Do not format the /dev/sdX1 block.
This is the BIOS/MBR partion.
Format the 500MB EFI system partition with a FAT32 filesystem:
#
mkfs.fat -F32 /dev/sdX2
Format the Linux partition with an
ext4
filesystem:
#
mkfs.ext4 /dev/sdX3
Install Base Package Set
Following the
Arch Way,
this guide intends to install the minimum number of packages necessary to
create a portable working Linux system.
mount
Mount the ext4 formatted partition as the root filesystem:
#
mkdir -p /mnt/usb
# mount /dev/sdX3 /mnt/usb
Mount the FAT32 formatted EFI partition to
boot:
#
mkdir /mnt/usb/boot
# mount /dev/sdX2 /mnt/usb/boot
pacstrap
Download and install the Arch Linux base packages:
#
pacstrap /mnt/usb linux linux-firmware base vim
fstab
Generate a new
fstab using
UUIDs
as source identifiers:
#
genfstab -U /mnt/usb > /mnt/usb/etc/fstab
chroot
All configuration can be performed within a
chroot
environment.
Begin by chrooting into the new system:
#
arch-chroot /mnt/usb
Inside a chroot the names of block devices may differ from the
host system. View the block device list and note the new name of the USB
device
/dev/sdY:
#
lsblk
locale
Use
tab-completion
to discover the appropriate entries for
region and
city:
#
ln -sf /usr/share/zoneinfo/region/city /etc/localtime
Generate
/etc/adjtime:
#
hwclock --systohc
Edit
/etc/locale.gen and uncomment your
desired language (for US English, uncomment
en_US.UTF-8 UTF-8):
#
vim /etc/locale.gen
Generate the locale information:
#
locale-gen
Set the
LANG variable in
/etc/locale.conf (for US
English,
localeline is
en_US.UTF-8):
#
echo LANG=localeline > /etc/locale.conf
hostname
Create the
/etc/hostname file containing
your desired
valid
hostname on a single line:
#
echo hostname > /etc/hostname
Edit
/etc/hosts to contain only the following content:
#
vim /etc/hosts
127.0.0.1 localhost
::1 localhost
127.0.1.1 hostname.localdomain hostname
mount options
To prevent excess writes to the USB and improve system performance, use the
noatime
mount option in
fstab. Open
/etc/fstab in an editor and change each
relatime or
atime option to
noatime:
#
vim /etc/fstab
# /dev/sdY3
UUID=uuid1 / ext4 rw,noatime 0 1
# /dev/sdY2
UUID=uuid2 /boot vfat rw,noatime,... 0 2
journal config
To prevent the systemd journal service from writing to
the USB, change the storage settings in
journald.conf.
Edit a drop-in file to contain the following content:
#
mkdir -p /etc/systemd/journald.conf.d
# vim /etc/systemd/journald.conf.d/10-volatile.conf
[Journal]
Storage=volatile
SystemMaxUse=16M
RuntimeMaxUse=32M
bootloader
Install the
grub and
efibootmgr packages:
#
pacman -S grub efibootmgr
Install GRUB for MBR/BIOS booting mode:
#
grub-install --target=i386-pc --boot-directory /boot --removable /dev/sdY
Install GRUB for UEFI booting mode:
#
grub-install --target=x86_64-efi --efi-directory /boot --boot-directory /boot --removable
Generate a GRUB configuration:
#
grub-mkconfig -o /boot/grub/grub.cfg
network interface names
To ensure that the main ethernet and wifi interfaces will always be named
eth0 and
wlan0, revert to traditional device naming:
#
ln -s /dev/null /etc/udev/rules.d/80-net-setup-link.rules
networking
Create a new
systemd-networkd
configuration file with the following content to automatically
establish wired network connections:
#
vim /etc/systemd/network/20-ethernet.network
[Match]
Name=en*
Name=eth*
[Network]
DHCP=yes
IPv6PrivacyExtensions=yes
[DHCPv4]
RouteMetric=100
[IPv6AcceptRA]
RouteMetric=100
Enable
networkd
and
resolved:
#
systemctl enable systemd-networkd.service
# systemctl enable systemd-resolved.service
Install and enable
iwd to allow user control over wireless interfaces:
#
pacman -S iwd
# systemctl enable iwd.service
Copy the wired network configuration file and edit it to the
following to handle wifi interfaces:
#
cp /etc/systemd/network/20-ethernet.network /etc/systemd/network/20-wlan.network
# vim /etc/systemd/network/20-wlan.network
[Match]
Name=wl*
[Network]
DHCP=yes
IPv6PrivacyExtensions=yes
[DHCPv4]
RouteMetric=600
[IPv6AcceptRA]
RouteMetric=600
Enable network time synchronization:
#
systemctl enable systemd-timesyncd.service
battery support
Install support for checking battery charge and state:
#
pacman -S acpi
root password
Set the root password:
#
passwd
user account
Create a new user account and set its password:
#
useradd -m user
#
passwd user
sudo
Install
sudo:
#
pacman -S sudo
Enable sudo for the sudo group by creating a new rule in
/etc/sudoers.d/:
#
EDITOR=vim visudo /etc/sudoers.d/10-sudo
%sudo ALL=(ALL) ALL
Ensure the sudo group exists and that
user is a member of it:
#
groupadd sudo
# usermod -aG sudo user
Install
polkit to allow various commands (
reboot
and
shutdown, among others) to be run by non-root users:
#
pacman -S polkit
logout
Logout of the chroot:
#
exit
Unmount the USB:
#
umount /mnt/usb/boot /mnt/usb && sync
Installation Complete!