A minimal set of dependencies are mandatory for building Gnuastro from the standard tarball release. If they are not present you cannot pass Gnuastro’s configuration step. The mandatory dependencies are therefore very basic (low-level) tools which are easy to obtain, build and install, see Mandatory dependencies for a full discussion.
If you have the packages of Optional dependencies, Gnuastro will have additional functionality (for example converting FITS images to JPEG or PDF). If you are installing from a tarball as explained in Quick start, you can stop reading after this section. If you are cloning the version controlled source (see Version controlled source), an additional bootstrapping step is required before configuration and its dependencies are explained in Bootstrapping dependencies.
Your operating system’s package manager is an easy and convenient way to download and install the dependencies that are already pre-built for your operating system. In Dependencies from package managers, we’ll list some common operating system package manager commands to install the optional and mandatory dependencies.