Scriptlets

Note that the %pretrans scriptlet will, in the particular case of system installation, run before anything at all has been installed. This implies that it cannot have any dependencies at all. For this reason, %pretrans is best avoided, but if used it MUST (by necessity) be written in Lua. See http://rpm.org/user_doc/lua.html for more information.

Sometimes a scriptlet needs to save some state from an earlier running scriptlet in order to use it at a later running scriptlet. This is especially common when trying to optimize the scriptlets. Examples:

To address these issues scriptlets that run earlier need to write out information that is used in %posttrans. We recommend using a subdirectory of %{_localstatedir}/lib/rpm-state/ for that. For instance, the eclipse plugin scripts touch a file in %{_localstatedir}/lib/rpm-state/eclipse/ when they’re installed. The %posttrans runs a script that checks if that file exists. If it does, it performs its action and then deletes the file. That way the script only performs its action once per transaction.

If RPM file triggers are not appropriate, complex scriptlets which are shared between multiple packages MAY be placed in RPM macros. This has two benefits:

When writing the macros, the FPC will still want to review the macros (and perhaps include the implementation of the macros in the guideline to show packagers what’s happening behind the scenes).

One principle that the FPC follows is that macros generally don’t contain the start of scriptlet tags (for instance, %pre) because this makes it difficult to do additional work in the scriptlet. This also means that a single macro can not be defined to do things in both %pre and %post. Instead, write one macro that performs the actions in %pre and a separate macro that performs the actions in %post. This principle makes it so that all spec files can use your macros in the same manner even if they already have a %pre or %post defined.

Of course, in the above situation it is better to use RPM file triggers if at all possible.

Packages which place linker configuration files in /etc/ld.so.conf.d MUST call ldconfig in %post and %postun (on all Fedora releases) even if they install no actual libraries. They MUST NOT use the %ldconfig, %ldconfig_post, %ldconfig_postun or %ldconfig_scriptlets macros to do this, since these macros do not have any effect on Fedora 28 and newer. Instead simply call /sbin/ldconfig directly in both %post and %postun as well as adding the necessary dependencies when necessary:

or, as part of existing %post or %postun scriptlets:

In addition, in Fedora 28 or newer the following applies: If the configuration file added to /etc/ld.so.conf.d specifies a directory into which other other packages may install files, and that directory is not located in the directory hierarchy beneath one of /lib, /usr/lib, /lib64 or /usr/lib64, then the package adding the configuration file MUST also include the following file triggers which cause ldconfig to be run automatically when necessary:

Replace DIRECTORIES with the space-separated list of directories which the package adds to the library search path via the configuration files in /etc/ld.so.conf.d.

These are discussed on a separate page

GConf is a configuration scheme currently used by the GNOME desktop. Programs which use it setup default values in a [NAME] .schemas file which is installed under %{_sysconfdir}/gconf/schemas/[NAME] .schemas. These defaults are then registered with the gconf daemon which monitors the configuration values and alerts applications when values the applications are interested in change. The schema files also provide documentation about what each value in the configuration system means (which gets displayed when you browse the database in the gconf-editor program).

For packaging purposes, we have to disable schema installation during build, and also register the values in the [NAME] .schemas file with the gconf daemon on installation and unregister them on removal. Due to the ordering of the scriptlets, this is a four step process.

Disabling the GConf installation during the package creation can be done like so:

The GCONF_DISABLE_MAKEFILE_SCHEMA_INSTALL environment variable suppresses the installation of the schema during the building of the package. An alternative for some packages is to pass a configure flag:

Unfortunately, this configure switch only works if the upstream packager has adapted their Makefile.am to handle it. If the Makefile.am is not configured, this switch won’t do anything and you’ll need to use the environment variable instead.

Here’s the second part:

In this section we uninstall old schemas during upgrade using one of two macros.

%gconf_schema_prepare is used for any current GConf schemas. It takes care of uninstalling previous versions of schemas that this package currently installs. It takes a space separated list of schema names without path or suffix that the package installs. Note that behind the scenes, this macro works with the %post scriptlet to only process GConf schemas if changes have occurred.

%gconf_schema_obsolete is used for schemas that this package previously provided but no longer does. It will deregister the old schema if it is present on the system. Nothing will happen if the old schema is not present. This macro takes a space separated list of schemas to uninstall. One example of using this might be if the package changed names. If the old schema was named foo.schemas and the new schema is named foobar.schemas you’d use:

The next section does the processing of the newly installed schemas:

%gconf_schema_upgrade takes a space separated list of schemas that the package currently installs just like %gconf_schema_prepare. Behind the scenes, it does the actual work of registering the new version of the schema and deregistering the old version.

The last section is for unregistering schemas when a package is removed:

When a package is upgraded rpm invokes the %pre scriptlet to register and deregister the schemas. When a package is uninstalled, the %preun scriptlet is used. %gconf_schema_remove takes the list of schemas that this package currently provides and removes them for us.

Packages containing systemd unit files need to use scriptlets to ensure proper handling of those services. Services can either be enabled or disabled by default. To determine which case your specific service falls into, please refer to FESCo’s policy here. On upgrade, a package may only restart a service if it is running; it may not start it if it is off. Also, the service may not enable itself if it is currently disabled.

/etc/shells is a text file which controls whether an application can be used as a system login shell of users. It contains the set of valid shells which can be used in the system. If you are packaging a new shell, you need to add entries to this file that reference the added shells. See: man 5 SHELLS for more information.

As this file can be edited by sysadmins, we need to first determine if relevant lines are already in the file. If they don’t already exist then we just need to echo the shell’s binary path to the file. Since the UsrMove Feature in Fedora 17 made /bin a symlink to /usr/bin we need to place both paths into the /etc/shells file. Here is an example of the scriptlet to package with shell named "foo":