From ArchWiki

[edit] What is ABS?

ABS is the Arch Build System. It is a 'ports-like' system for building software from source and subsequently packaging it. While pacman is the specialized Arch tool for binary package management, (including packages built with ABS), ABS is the specialized Arch tool for compiling source into an installable .pkg.tar.gz package.

[edit] What is a ports-like system?

'Ports' is a system used by *BSD, which allows source packages to be downloaded, unpacked, patched, compiled and installed. A 'port' is merely a small directory on the user's computer, named after the corresponding software to be installed, which contains a few files with instructions for downloading and installing an application from source, typically by navigating to the directory, or port, and doing 'make' and 'make install'. The system will then download, compile and install the desired software.

[edit] ABS is a similar concept.

ABS is made up of a directory tree, (the ABS Tree), residing under /var/abs, which contains many subdirectories, each within a category, and each named by their respective, buildable package. This tree represents (but does not contain) all official Arch software, retrievable through the SVN system. You may refer to each package-named subdirectory as an 'ABS', much the way one would refer to a 'port'. These ABS, or subdirectories, do not contain the software package, nor the source, but rather, contain a PKGBUILD file, (and sometimes other files). A PKGBUILD is a simple build script- a text file containing the compilation and packaging instructions as well as the URL of the appropriate source tarball to be downloaded. (The most important component of ABS are PKGBUILDs.) By issuing the ABS makepkg command, the software is first compiled, and then packaged within the build directory before being installed. In this way, pacman, the Arch Linux package manager, is utilized for package installation, upgrade and removal.

[edit] Quick Walkthrough

Install abs with pacman -Sy abs. Running 'abs' as root creates the ABS tree by synchronizing with the Arch Linux server. If you wanted to build a package from source you would copy the build files (usually residing under /var/abs/<repo>/<pkgname>) to a build directory, navigate to that directory and do makepkg. According to instructions in the PKGBUILD, makepkg will download the appropriate source tarball, unpack it, patch if desired, compile according to CFLAGS specified in makepkg.conf, and finally compress the built files into a package with the extension .pkg.tar.gz. PKGBUILDs may be customized to suit your unique configuration needs, or for applying patches. Installing is as easy as doing pacman -U <.pkg.tar.gz file>. Package removal is also handled by pacman.

You may also use makepkg to make your own custom packages from the AUR or third party sources. (See the package making wiki article)

With the ABS Tree in place, an Arch user has all available Arch software at their fingertips, to compile from source, automatically package as a .pkg.tar.gz, and finally, install with pacman.

[edit] ABS Overview

'ABS' may be used as an umbrella term, since it includes and relies on several other components. Therefore, though not technically accurate, 'ABS' can refer to the following structure and tools as a complete toolkit:

• The ABS tree: The ABS directory structure under /var/abs/ on your (local) machine. It contains many subdirectories, named for all available official Arch Linux software from repositories specified in /etc/abs.conf, but not the packages themselves.
• ABS: A set of tools to retrieve and build official Arch Linux PKGBUILDs. Example PKGBUILDs are also included.
• PKGBUILDs: Text build script files residing under the ABS directories, or that are custom made, with instructions for building packages and the URL of the sources.
• makepkg: ABS shell command tool which reads the PKGBUILDs, automatically downloads and compiles the sources and creates a .pkg.tar.gz.
• Pacman: Pacman is completely separate, but is necessarily invoked either by makepkg or manually, to install and remove the built packages, and for fetching dependencies.

• AUR: The Arch User-Community Repository is separate from ABS but AUR [unsupported] PKGBUILDs can be built using the ABS makepkg tool, to compile and package up software. The AUR contains over 8000 user-contributed PKGBUILDs for software which is unavailable as an official Arch package. If you need to build a package outside the official Arch tree, chances are it is in the AUR.

[edit] Why would I want to use ABS?

The Arch Build System (ABS for short) is used to

• Recompile a package
• Make and install new packages from source, of software for which no packages are yet available (See The Arch package making HOW-TO - with guidelines)
• Customize existing packages to fit your needs (enabling or disabling options, patching)
• Rebuild your entire system using your compiler flags, "a la FreeBSD"
• Cleanly build and install your own custom kernel. (See Kernel Compilation)
• Get kernel modules working with your custom kernel.
• Easily compile and install a newer, older, beta, or development version of an Arch package by editing the version number in the PKGBUILD

ABS is not necessary to use Arch Linux, but it is useful for automating certain tasks of source compilation.

This how-to tries to give you an overview of ABS and Arch packages; it's not a complete reference guide! If you want more, read the man pages.

[edit] Get Started: Install Packages

To use abs, you first need to install abs from the core repository; this can be done simply by:

pacman -Sy abs

This will grab any necessary dependencies.

[edit] /etc/abs.conf

As root, edit /etc/abs.conf to include your desired repositories:

vim /etc/abs.conf

or:

nano -w /etc/abs.conf

Remove the ! in front of the appropriate repos, e.g.:

REPOS=(core extra unstable community !testing)

[edit] Create the ABS tree

As root, do:

abs

Your ABS tree is now created under /var/abs. Note the appropriate branches of the ABS tree now exist and correspond to the ones you specified in /etc/abs.conf.

The abs command should also be used to periodically sync and update your ABS Tree.

[edit] /etc/makepkg.conf

/etc/makepkg.conf specifies global environment variables and compiler flags which you may wish to edit if you are using an SMP system, or to specify other desired optimizations. The default settings are for i686 and x86_64 optimizations which will work fine for those architectures on single-cpu systems. (The defaults will work on SMP machines, but will only utilize one core/CPU when compiling- see Safe Cflags.).

[edit] The ABS tree

When you run abs for the first time, it synchronizes the ABS tree with the Arch Linux server. So what exactly is the ABS tree? It is located under /var/abs and looks like this:

| -- core/
|     || -- base/
|     ||     || -- acl/
|     ||     ||     || -- PKGBUILD
|     ||     || -- attr/
|     ||     ||     || -- PKGBUILD
|     ||     || -- ...
|     || -- devel/
|     ||     || -- abs/
|     ||     ||     || -- PKGBUILD
|     ||     || -- autoconf/
|     ||     ||     || -- PKGBUILD
|     ||     || -- ...
|     || -- ...
| -- extra/
|     || -- daemons/
|     ||     || -- acpid/
|     ||     ||     || -- PKGBUILD
|     ||     ||     || -- ...
|     ||     || -- apache/
|     ||     ||     || -- ...
|     ||     || -- ...
|     || -- ...
| -- community/
|     || -- ...

So the ABS tree has exactly the same structure as the package database:

• first-level directory represents categories
• second-level directories represents the ABS themselves, whose names actually correspond to the packages you want to build
• PKGBUILD files contain all information needed concerning the package
• Further, an ABS directory can contain patches and/or other files needed for building the package.

It is important to understand that the actual source code for the package is not present in the ABS directory. Instead, the PKGBUILD file contains a URL from which ABS will automatically download from.

[edit] Create a Build Directory

You must create a build directory, where the actual compiling will take place. This is where you'll do everything; you should never modify the ABS Tree by building within it, as data will be lost (overwritten) on each abs update. It is good practice to use your home directory, though some Arch users prefer to create a 'local' directory under /var/abs/, owned by normal user. Copy the ABS from the tree (var/abs/branch/category/pkgname) to the build directory, /path/to/build/dir.

Create your build directory. e.g.:

mkdir -p /home/yourusername/abs

NOTE: The first download of the abs tree is the biggest, then only minor updates are needed, so don't be afraid about the data to download if you've got only a 56k connection; it's only text files and is compressed during the transfer.

Now that you know what the ABS tree is, how can we use it ?

[edit] The build function, traditional method

If you're not familiar with compiling from source, you should know that most packages (but not all) can be built from source in this traditional way:

• Download source tarball from remote server, using web browser, ftp, wget or alternate method.
• decompress the source file:

  tar -xzf foo-0.99.tar.gz
  tar -xjf foo-0.99.tar.bz2

• enter the directory

cd foo-0.99

• configure the package: generally, there is a little script called configure in the source directory that is used to configure the package (add or remove support for things, choose the install destination, etc.) and check that your computer has all the software needed by the package. It can be run by:

./configure [[option]]

You should first try the help to better understand how it works:

./configure --help

If a --prefix option is not passed to the script, most scripts will use /usr/local as the install path, but others will use /usr. For the sake of consistency, it is generally advised to pass the --prefix=/usr/local option. It is good practice to install personal programs in /usr/local, and to have the ones being managed by the distro, in /usr. This ensures personal program versions can coexist with those being managed by the distro's package manager- in Arch's case, pacman.

./configure --prefix=/usr/local

• compile the sources:

make

• install

make install

• Uninstalling would be accomplished by entering the source directory and running:

make uninstall

However, you should always read the INSTALL file to know how the package should be built and installed! Not all packages use the configure; make; make install system!

[edit] The build function, the ABS way

ABS is an elegant tool which allows for powerful assistance and customization for the build process, and creates a pacman-trackable package file for installation. The ABS method involves copying an ABS from the Tree to a build directory, and doing makepkg. In our example, we will build the slim display manager package.

• 1. Copy the slim ABS from the ABS Tree to a build directory.

cp -r /var/abs/extra/x11/slim/ /home/yourusername/abs

• 2. Navigate to the build directory

cd /home/yourusername/abs/slim

• 3. Do makepkg as normal user:

makepkg -c

Install as root:

# pacman -U slim 1.3.0-2-i686.pkg.tar.gz

That's it. You have just built slim from source and cleanly installed it to your system with pacman. Package removal is also handled by pacman- (pacman -R slim)

• What is happening:

Essentially, the same steps are being executed, generally including the ./configure, make, make install, steps, but the software is installed into a fake root environment. (A fake root is simply a subdirectory within the build directory that functions and behaves as the system's root directory. In conjunction with the fakeroot program, makepkg creates a fake root directory, and installs the compiled binaries and associated files into it, with root as owner.) The fake root, or subdirectory tree containing the compiled software, is then compressed into an archive with the extension .pkg.tar.gz, or a package. When invoked, pacman then extracts the package (installs it) into the system's real root directory, (/). Simple.

• The ABS method adds a level of convenience and automation, while still maintaining complete transparency and control of the build and installation functions by including them in the PKGBUILD.

See ABS PKGBUILD Explained for a complete overview of a sample PKGBUILD.

[edit] More ABS and related info

• ABS PKGBUILD Explained
• Makepkg
• The Arch package making HOW-TO - with guidelines
• Safe Cflags
• Kernel Compilation with ABS
• ArchLinux User-community Repository (AUR)
• Custom local repository with ABS and gensync