RPM looks for rpmrc files in four places:
The first three files are read in the order listed, such that if a given rmprc entry is present in each file, the value of the entry read last is the one used by RPM. This means, for example, that an entry in .rpmrc in the user's login directory will always override the same entry in /etc/rpmrc. Likewise, an entry in /etc/rpmrc will always override the same entry in /usr/lib/rpmrc.
If the --rcfile option is used, then only /usr/lib/rpmrc and the file following the --rcfile option are read, in that order. The /usr/lib/rpmrc file is always read first. This cannot be changed.
Let's look at each of these files, starting with /usr/lib/rpmrc.
The file /usr/lib/rpmrc is always read. It contains information that RPM uses to set some default values. This file should never be modified! Doing so may cause RPM to operate incorrectly.
After this stern warning, we should note that it's perfectly all right to look at it. Here it is, in fact:
############################################################# # Default values, often overridden in /etc/rpmrc dbpath: /var/lib/rpm topdir: /usr/src/redhat tmppath: /var/tmp cpiobin: cpio defaultdocdir: /usr/doc ############################################################# # Please send new entries to rpm-list@redhat.com ############################################################# # Values for RPM_OPT_FLAGS for various platforms optflags: i386 -O2 -m486 -fno-strength-reduce optflags: alpha -O2 optflags: sparc -O2 optflags: m68k -O2 -fomit-frame-pointer ############################################################# # Canonical arch names and numbers arch_canon: i986: i986 1 arch_canon: i886: i886 1 arch_canon: i786: i786 1 arch_canon: i686: i686 1 arch_canon: i586: i586 1 arch_canon: i486: i486 1 arch_canon: i386: i386 1 arch_canon: alpha: alpha 2 arch_canon: sparc: sparc 3 arch_canon: sun4: sparc 3 arch_canon: sun4m: sparc 3 arch_canon: sun4c: sparc 3 # This is really a place holder for MIPS. arch_canon: mips: mips 4 arch_canon: ppc: ppc 5 # This is really a place holder for 68000 arch_canon: m68k: m68k 6 # This is wrong. We really need globbing in here :-( arch_canon: IP: sgi 7 arch_canon: IP22: sgi 7 arch_canon: 9000/712: hppa1.1 9 arch_canon: sun4u: usparc 10 ############################################################# # Canonical OS names and numbers os_canon: Linux: Linux 1 os_canon: IRIX: Irix 2 # This is wrong os_canon: SunOS5: solaris 3 os_canon: SunOS4: SunOS 4 os_canon: AmigaOS: AmigaOS 5 os_canon: AIX: AIX 5 os_canon: HP-UX: hpux10 6 os_canon: OSF1: osf1 7 os_canon: FreeBSD: FreeBSD 8 ############################################################# # For a given uname().machine, the default build arch buildarchtranslate: osfmach3_i986: i386 buildarchtranslate: osfmach3_i886: i386 buildarchtranslate: osfmach3_i786: i386 buildarchtranslate: osfmach3_i686: i386 buildarchtranslate: osfmach3_i586: i386 buildarchtranslate: osfmach3_i486: i386 buildarchtranslate: osfmach3_i386: i386 buildarchtranslate: i986: i386 buildarchtranslate: i886: i386 buildarchtranslate: i786: i386 buildarchtranslate: i686: i386 buildarchtranslate: i586: i386 buildarchtranslate: i486: i386 buildarchtranslate: i386: i386 buildarchtranslate: osfmach3_ppc: ppc ############################################################# # Architecture compatibility arch_compat: alpha: axp arch_compat: i986: i886 arch_compat: i886: i786 arch_compat: i786: i686 arch_compat: i686: i586 arch_compat: i586: i486 arch_compat: i486: i386 arch_compat: osfmach3_i986: i986 osfmach3_i886 arch_compat: osfmach3_i886: i886 osfmach3_i786 arch_compat: osfmach3_i786: i786 osfmach3_i686 arch_compat: osfmach3_i686: i686 osfmach3_i586 arch_compat: osfmach3_i586: i586 osfmach3_i486 arch_compat: osfmach3_i486: i486 osfmach3_i386 arch_compat: osfmach3_i386: i486 arch_compat: osfmach3_ppc: ppc arch_compat: usparc: sparc
Quite a bunch of stuff, isn't it? With the exception of the first five lines, which indicate where several important directories and programs are located, the remainder of this file contains rpmrc entries that are related to RPM's architecture and operating system processing. As you might imagine, any tinkering here will probably not be very productive, so leave any modifications here to the RPM developers.
Next, we have /etc/rpmrc.
The file /etc/rpmrc, unlike /usr/lib/rpmrc, is fair game for modifications and additions. In fact, /etc/rpmrc isn't created by default, so its contents are entirely up to you. It's the perfect place to keep rpmrc entries of a system-wide or global nature.
The vendor entry is a great example of a good candidate for inclusion in /etc/rpmrc. In most cases, a particular system is dedicated to building packages for one vendor. In these instances, setting the vendor entry in /etc/rpmrc is best.
Next in the hierarchy is a file named .rpmrc, residing in the user's login directory.
As you might imagine, a file called .rpmrc in a user's login directory is only going to be read by that user when he or she runs RPM. Like /etc/rpmrc, this file is not created by default, but it can contain the same rpmrc entries as the other files. The packager entry, which should contain the name and contact information for the person who built the package, is an appropriate candidate for /.rpmrc.
The --rcfile option is best used only when a totally different RPM configuration is desired for one or two packages. Since the only other rpmrc file read is /usr/lib/rpmrc with its low-level default settings, the file specified with the --rcfile option will have to be more comprehensive than either /etc/rpmrc or /.rmprc.