7. The comps file

7.1. Format of comps file in RedHat versions < 6.1

The comps file currently starts with a header describing the version of the comps format, followed by an empty line.

0.1 <empty line>

After this, the components are listed, separated by empty lines:

<component 1> <empty line> <component 2> <empty line> .... <component n> <empty line> EOF

Each component has the following definition:

(0|1) (--hide)? <name> <RPM 1> <RPM 2> ... <RPM n> end

Before the name of each component, 0 or 1 is given. A value of 1 here means that the component is chosen by default, and 0 means it's not. The option --hide means that you will not see the entry, unless you choose "expert" installation. The first component is called "Base", and that is special, in the sense that it must be present and it does not show up in the dialog (you can't deselect the base installation, which makes sense...). Next follows a list of rpm packages belonging to that component. Note that this is the package name stored in the rpm file, and not any part of the file name of the package (although it should be the same by convention).

By adding your packages to the comps file, you can customize your own distribution, and make sure that your packages will be installed by default. One thing to be careful about is interdependence among your packages, but here, you are on your own :-) A word of warning: be careful not to add or remove extra whitespace in the file. Examine the existing comps file (make a copy of the original) to see how it's done (or check i386/misc/src/install/pkgs.c if you want to see how the file is parsed).

7.2. Format of comps file in RedHat version 6.1

With RedHat version 6.1, the format of the comps file has changed. The decoding takes place in ${RHROOT}/${ARCH}/misc/src/anaconda/comps.py. I didn't analyze yet this python script and the following rules were obtained only by reading the file and testing some configurations for it.

In release 6.1, the definition of component is extended to include some more optional elements beside the <RPM> ones. These elements are:

<arch-dependent-RPM 1> ... <arch-dependent-RPM n> <required-component 1> ... <required-component n> <component-dependent-RPM 1> ... <component-dependent-RPM n>

An <arch-dependent-RPM> defines a dependency between a package and specific architecture and has the following definition:

(!)?arch: <RPM>

So it can, for example, present itself, in the real world, as:

!alpha: kernelcfg

which means: if architecture is not alpha then install package kernelcfg.

Or as:

i386: mkbootdisk

which means if architecture is i386 then install package mkbootdisk

A <required-component1> enforces the dependency from another component and is defined as:

@ <component>

So, for example, if inside a component definition you find the following line:

@ Networked Workstation

it means that the component itself needs the installation of another component named Networked Workstation.

A <component-dependent-RPM> is used to select the installation of some additional packages for a component, given the presence of another component. Its definition is as follows:

? <component> { <RPM 1> ... <RPM n> }

So if, for example, in a component definition, you happen to read the following lines:

? KDE { kpppload }

then if the KDE component is installed, the package kpppload will be installed together with the packages included in the component the definition was found in.

7.3. Format of comps file in RedHat version 6.2

With RedHat version 6.2, the format of the comps file has, apparently, changed just slightly. The decoding takes place in ${RHROOT}/${ARCH}/misc/src/anaconda/comps.py even in this case. Once again, I didn't analyze yet this python script and the following rules were obtained only by reading the file and testing some configurations for it.

In release 6.2, the definition of component is extended to include two more optional elements which are:

<lang-dependent-RPM 1> ... <lang-dependent-RPM n> <arch-dependent-component 1> ... <arch-dependent-component n>

A <lang-dependent-RPM> is needed to specify the installation of a package in case a specific language was selected. It's defined as:

(lang <language>): <RPM>

For example, the following line:

(lang ja_JP)): locale-ja

means: if the Japanese language is selected, then install the locale-ja package together with the other packages installed for the current component.

An <arch-dependent-component> extends the concept of <arch-dependent-RPM> introduced in release 6.1 to an entire component, as you can understand reading the definition:

(!)?arch: <component>

7.4. Format of comps file in RedHat version 7.3

With RedHat version 7.3, the format of the comps file has gained some more syntactical power. The decoding takes place (again) in the comps.py script, which you can now find in the /usr/lib/anaconda/ directory if you have installed the anaconda package. The dependencies on a language or an architecture by a component or a package can now be joined with the and operator. For example:

(arch !s390 and arch !s390x and arch !ia64): readline2.2.1

which means if architecture is not any of s390, s390x, ia64 then install the package readline2.2.1. This can be done with components instead of packages and languages instead of architectures. All this, is definitely more than enough for the simple examples of customization of the default installation which will be presented in the next section.

7.5. Format of comps file in RedHat version 8.0 and 9

With RedHat version 8.0 and 9, the format of the comps file has changed completely and now an XML file, whose name is comps.xml, is used. Details on the file syntax can be found in the anaconda comps section of the RedHat website.