Arch Linux: Practical Reference

This page is the practical side: commands, maintenance and fixes. For the background on Arch's philosophy, the rolling model and the AUR, read the Arch Linux overview. To install it, follow how to install Arch Linux.

Everyday pacman commands

For the same tasks on apt, dnf and zypper, see package managers compared.

A safe update routine

1. Check archlinux.org/news for anything that needs manual intervention.
2. Upgrade everything and read pacman's output, including warnings about .pacnew files:

   sudo pacman -Syu

3. Merge configuration changes. When a package ships a new default config and you've edited yours, pacman saves the new one as file.pacnew:

   sudo pacman -S pacman-contrib
   sudo pacdiff

4. Reboot after kernel, systemd, glibc or graphics driver updates.
5. Clean the package cache occasionally (keeps the last three versions of each package):

   sudo paccache -r
   # or enable the weekly timer
   sudo systemctl enable --now paccache.timer

6. Remove orphans after reviewing the list:

   pacman -Qdtq
   sudo pacman -Rns $(pacman -Qdtq)

Keyring and mirrors

Packages are signed by Arch packagers whose keys come from the archlinux-keyring package. On a system that hasn't been updated for a while, new packagers' signatures can't be verified yet and pacman refuses the upgrade. Update the keyring first:

sudo pacman -Sy archlinux-keyring
sudo pacman -Su

This is the one accepted case of -Sy followed by a single package, because -Su immediately completes the upgrade. If signatures still fail, see pacman invalid or corrupted package (PGP signature).

Slow or failing downloads usually mean a bad mirror. reflector rewrites the mirror list with fast, up-to-date HTTPS mirrors:

sudo pacman -S reflector
sudo cp /etc/pacman.d/mirrorlist /etc/pacman.d/mirrorlist.bak
sudo reflector --country 'United States,Canada' --protocol https --latest 20 --sort rate --save /etc/pacman.d/mirrorlist
sudo pacman -Syyu

Replace the countries with ones near you. -Syy forces a database refresh after changing mirrors.

The AUR

Software not in the official repositories is often in the AUR as a PKGBUILD. Building one by hand:

sudo pacman -S --needed base-devel git
git clone https://aur.archlinux.org/<package>.git
cd <package>
less PKGBUILD          # read it before building
makepkg -si

Helpers like yay and paru automate this and update AUR packages along with the system (paru or yay on its own runs a full upgrade). They are themselves AUR packages, are not supported by Arch, and should never be run with sudo. When an AUR package breaks after a system upgrade, rebuilding it against the new libraries usually fixes it.

Kernels, drivers and boot

• Keep a fallback kernel. Installing linux-lts next to linux gives you a second boot entry if a new kernel regresses. Install the matching headers (linux-headers, linux-lts-headers) if you use DKMS modules.
• NVIDIA: for Turing (RTX 20 / GTX 16) and newer, install nvidia-open (or nvidia-open-dkms for non-default kernels) plus nvidia-utils. Older Maxwell and Pascal cards need the legacy 580 branch from the AUR or nouveau. Black screens after a driver change are covered in NVIDIA black screen fixes.
• Microcode: install intel-ucode or amd-ucode and regenerate the bootloader config so it's loaded early.
• Initramfs: mkinitcpio builds it by default; rebuild manually with sudo mkinitcpio -P.
• Boot parameters: see setting kernel parameters for GRUB and systemd-boot.

Common problems and fixes

Recovering an unbootable system

# from the Arch ISO
mount /dev/<root-partition> /mnt
mount /dev/<efi-partition> /mnt/boot     # or /mnt/efi, depending on your layout
arch-chroot /mnt
grep -i upgraded /var/log/pacman.log | tail -30
pacman -Syu                                  # finish an interrupted upgrade
mkinitcpio -P
exit
reboot

Partition names come from lsblk -f. If GRUB itself is broken, use fixing grub rescue.

Arch compared with the alternatives

Arch gives you the newest packages and full control, at the cost of doing your own integration and reading the news before updates. If you want new software with more defaults chosen for you and a predictable release every six months, Fedora is the usual alternative. For a system you rarely touch, Debian stable or Ubuntu LTS fits better. openSUSE Tumbleweed is the other major rolling distribution, with automatic Btrfs snapshots; see the openSUSE reference.

Frequently asked questions