A PKGBUILD is a shell script containing the build information required by Arch Linux packages.

Packages in Arch Linux are built using the makepkg utility. When makepkg is run, it searches for a PKGBUILD file in the current directory and follows the instructions therein to either compile or otherwise acquire the files to build a package archive (pkgname.pkg.tar.xz). The resulting package contains binary files and installation instructions, readily installable with pacman.

Mandatory variables are pkgname, pkgver, pkgrel, and arch. license is not strictly necessary to build a package, but is recommended for any PKGBUILDs shared with others, as makepkg will produce a warning if not present.

It is a common practice to define the variables in the PKGBUILD in same order as given here. However, this is not mandatory, as long as correct Bash syntax is used.