Building in a clean chroot prevents missing dependencies in packages, whether due to unwanted linking or packages missing in thedepends array in aPKGBUILD file. It also allows users to build a package for the stable repositories (core,extra) while having packages fromcore-testing orextra-testing installed.

To quickly build a package in a clean chroot without any further tinkering, one can use the helper scripts from thedevtools package.

These helper scripts—for example,pkgctl build—should be called in the same directory where thePKGBUILD file is, just like with makepkg. For instance,extra-x86_64-build automatically sets up a chroot from a clean chroot matrix in/var/lib/archbuild, updates it, and builds a package for the extra repository. For multilib builds there is justmultilib-build without an architecture. Consult the table below for information on which script to use when building for a specific repository and architecture.

The-c parameter resets the chroot matrix, which can be useful in case of breakage. It is not needed for building in a clean chroot.

Thedevtools package provides tools for creating and building within clean chroots. Install it if not done already.

To make a clean chroot, create a directory in which the chroot will reside. For example,$HOME/chroot.

$ mkdir ~/chroot

Define theCHROOT variable:

$ CHROOT=$HOME/chroot

Now create the chroot (the sub directoryroot is required because the$CHROOT directory will get other sub directories for clean working copies):

$ mkarchroot $CHROOT/root base-devel

Edit~/.makepkg.conf to set the packager name and any makeflags. Also adjust themirrorlist in$CHROOT/root/etc/pacman.d/mirrorlist and enable thetesting repositories in$CHROOT/root/etc/pacman.conf, if desired.

Alternatively, provide a custompacman.conf andmakepkg.conf with the following:

$ mkarchroot -C <pacman.conf> -M <makepkg.conf> $CHROOT/root base-devel

Firstly, make sure the base chroot ($CHROOT/root) is up to date:

$ arch-nspawn $CHROOT/root pacman -Syu

Then, build a package by callingmakechrootpkg in the directory containing itsPKGBUILD file:

$ makechrootpkg -c -r $CHROOT

To build a package with dependencies unavailable from the repositories enabled in$CHROOT/root/pacman.conf, pre-install them to the working chroot with-Ipackage:

$ makechrootpkg -c -r $CHROOT -I build-dependency-1.0-1-x86_64.pkg.tar.zst -I required-package-2.0-2-x86_64.pkg.tar.zst

To pass arguments tomakepkg, list them after an end-of-options marker--. E.g., to force acheck():

$ makechrootpkg -c -r $CHROOT -- --check

The cleanest way to handle a major rebuild is to use thestaging repositories. Build the first package againstextra and push it tostaging. Then rebuild all following packages againststaging and push them there.

If you cannot usestaging, you can build against custom packages using a command like this:

# extra-x86_64-build -- -I ~/packages/foobar/foobar-2-1-any.pkg.tar.zst

You can specify more than one package to be installed using multiple-I arguments.

A simpler, but dirtier way to handle a major rebuild is to install all built packages in the chroot, never cleaning it. Build the first package using:

# extra-x86_64-build

And build all following packages using:

# makechrootpkg -n -r /var/lib/archbuild/extra-x86_64

Running namcap (the-n argument) implies installing the package in the chroot.*-build also does this by default.

If the system has enough RAM, it is possible to specify atmpfs for thedevtools build scripts:

# mount --mkdir -t tmpfs -o defaults,size=20G tmpfs /mnt/chroots/arch# extra-x86_64-build -c -r /mnt/chroots/arch

Just delete the chroot directory and its corresponding.lock file.

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