4.4. RPM conditionals
RPM Conditionals enable conditional inclusion of various sections of the SPEC file.
Conditional inclusions usually deal with:
- Architecture-specific sections
- Operating system-specific sections
- Compatibility issues between various versions of operating systems
- Existence and definition of macros
4.4.1. RPM conditionals syntax
RPM conditionals use the following syntax:
If expression is true, then do some action:
%if expression … %endif
If expression is true, then do some action, in other case, do another action:
%if expression … %else … %endif
4.4.2. The %if conditionals
This section provides examples of using the %if RPM conditionals.
Exemple 4.3. Using the %if conditional to handle compatibility between Red Hat Enterprise Linux 8 and other operating systems
%if 0%{?rhel} == 8
sed -i '/AS_FUNCTION_DESCRIBE/ s/^/#/' configure.in
sed -i '/AS_FUNCTION_DESCRIBE/ s/^/#/' acinclude.m4
%endif
This conditional handles compatibility between RHEL 8 and other operating systems in terms of support of the AS_FUNCTION_DESCRIBE macro. If the package is built for RHEL, the %rhel macro is defined, and it is expanded to RHEL version. If its value is 8, meaning the package is build for RHEL 8, then the references to AS_FUNCTION_DESCRIBE, which is not supported by RHEL 8, are deleted from autoconfig scripts.
Exemple 4.4. Using the %if conditional to handle definition of macros
%define ruby_archive %{name}-%{ruby_version}
%if 0%{?milestone:1}%{?revision:1} != 0
%define ruby_archive %{ruby_archive}-%{?milestone}%{?!milestone:%{?revision:r%{revision}}}
%endif
This conditional handles definition of macros. If the %milestone or the %revision macros are set, the %ruby_archive macro, which defines the name of the upstream tarball, is redefined.
4.4.3. Specialized variants of %if conditionals
The %ifarch conditional, %ifnarch conditional and %ifos conditional are specialized variants of the %if conditionals. These variants are commonly used, hence they have their own macros.
The %ifarch conditional
The %ifarch conditional is used to begin a block of the SPEC file that is architecture-specific. It is followed by one or more architecture specifiers, each separated by commas or whitespace.
Exemple 4.5. An example use of the %ifarch conditional
%ifarch i386 sparc … %endif
All the contents of the SPEC file between %ifarch and %endif are processed only on the 32-bit AMD and Intel architectures or Sun SPARC-based systems.
The %ifnarch conditional
The %ifnarch conditional has a reverse logic than %ifarch conditional.
Exemple 4.6. An example use of the %ifnarch conditional
%ifnarch alpha … %endif
All the contents of the SPEC file between %ifnarch and %endif are processed only if not done on a Digital Alpha/AXP-based system.
The %ifos conditional
The %ifos conditional is used to control processing based on the operating system of the build. It can be followed by one or more operating system names.
Exemple 4.7. An example use of the %ifos conditional
%ifos linux … %endif
All the contents of the SPEC file between %ifos and %endif are processed only if the build was done on a Linux system.
