RPM stands for RedHat Package Manager. RPM is a system for installing and managing software & most common software package manager used for Linux distributions. Because it allows you to distribute software already compiled, a user can install the software with a single command.

There are two flavors of RPMs: binary & source code. Source code are designated by ending with -src.rpm rather than just .rpm

Installing source rpms (SRPM):
Unlike ordinary packages, they can't be uninstalled using RPM. SRPM packages are not under the control of the RPM database. All RPM does is copy the files contained in the package to the hard disk. SRPMs are not listed in the RPM database and not marked as installed in YaST's package selection forms.

A source RPM (SRPM) package typically contains a gzipped tar archive with the source files, and an RPM spec file

Govinda:/users/techno/downloads # ls -l xmms*src*
-rw------- 1 techno users 4032244 2004-09-28 12:43 xmms-1.2.10-1.src.rpm

Listing the contents of a source rpm:
Govinda:/users/techno/downloads # rpm -qpl xmms-1.2.10-1.src.rpm
xmms-1.2.10.tar.gz
xmms.spec

Source rpm can be installed just like any other rpm with "-ivvh" flags
Govinda:/users/techno/downloads # rpm -ivvh xmms-1.2.10-1.src.rpm
D: counting packages to install
D: found 1 packages
D: looking for packages to download
D: retrieved 0 packages
D: New Header signature
D: Signature size: 180
D: Signature pad : 4
D: sigsize : 184
D: Header + Archive: 4031964
D: expected size : 4031964
D: found 1 source and 0 binary packages
D: New Header signature
D: Signature size: 180
D: Signature pad : 4
D: sigsize : 184
D: Header + Archive: 4031964
D: expected size : 4031964
D: installing a source package
D: sources in: /usr/src/packages/SOURCES
D: spec file in: /usr/src/packages/SPECS
D: file: xmms-1.2.10.tar.gz action: unknown
D: file: xmms.spec action: unknown
xmms ##################################################
GZDIO: 494 reads, 4041876 total bytes in 0.020 secs

Verbose output shows that the sources are under: /usr/src/packages/SOURCES & the specification (SPEC) file is under: /usr/src/packages/SPECS
Govinda:/users/techno/downloads # ls -l /usr/src/packages/SOURCES/xmms*
-rw-rw-r-- 1 root root 4034832 2004-02-23 13:54 /usr/src/packages/SOURCES/xmms-1.2.10.tar.gz
Govinda:/users/techno/downloads # ls -l /usr/src/packages/SPECS/xmms*
-rw-rw-r-- 1 root root 6665 2004-02-23 13:57 /usr/src/packages/SPECS/xmms.spec

The RPM build tree
-----------------------
To use RPM as a tool for building software packages, we must follow some rules in terms of locations for the source code used to build this software. Expect two different kinds of input to build a package:

(1) Source
Of course we need source code to build the package (assume that we got the source without any customizations). Usually these sources are distributed as compresse tar file (tgz). RPM can handle other formats as well

(2) Spec file
The spec file is the heart of RPM's package building process. It's like a make file, as it contains information on how to build the package. But it's settled on a much higher level and contains all meta information about the package. .spec is the extension for SPEC files

Note:
It is not uncommon to have a patch included in the source files

RPM directories for building packages
----------------------------------------------------------------------------------
Directory Contents
----------------------------------------------------------------------------------
SPECS Spec files
SOURCES Source and patch files
BUILD Used to build (unpack and compile) the software package
RPMS Contains the build RPM files (sorted by architecture)
SRPMS Contains the build SRPM files

RPM Build Stages
---------------------------------------------------------------------
Flag Stage
---------------------------------------------------------------------
p prep (unpack sources and apply patches)
l list check (do some cursory checks on %files)
c compile (prep and compile)
i install (prep, compile, install)
b binary package (prep, compile, install, package)
a bin/src package (prep, compile, install, package)

Building the Package
-------------------------
After the SRPM is installed, we can continue with the RPM build stages. RPM builds packages in 4 stages:

(1) Preparation
The prep-stage is where the actual work building the binary package starts. In this stage the sources are unpacked and the patches to the sources are applied (if any). If the package builder had forseen any additional preparations which have to be done prior to compiling the sources, they will be executed in this stage

(2) Compilation
After the sources are prepared, the compilation process can take place. In this stage all source files are compiled and linked to the resulting binaries, libraries, etc.

(3) Installation
This stage installs the new software package on the system. At this point the build process changes your actual system. It puts the binaries, libraries, configuration files, etc. in the places where they belong for the new software package. No entry is made in the RPM database reflecting this installation.

Quick Note:
Installing binaries from a source package doesn't include that the package is under the control of the RPM database

(4) Packaging
The last step is to create the RPM and the SRPM for the new software package. You can turn off this stage when you just want to compile and install the package. Better create the new SRPM, if sources were modified ange the behavior of the binaries

RPM Build Options
------------------------------------------------------------------------------------
Option Meaning
------------------------------------------------------------------------------------
-bstage-spec or
-tstage-tarball build package (see table 34-2 for stage spec)
--short-circuit skip straight to specified stage (only for c,i)
--clean remove build tree when done
--rmsource remove sources and spec file when done
--buildrootdir use dir as the build root
--buildarcharch build the packages for architecture arch
--buildosos build the packages for operating system os
--test do not execute any stages
--timechecksecs set the time check to secs seconds (0 disables)
--rebuildsrpm install source package, build binary package and remove
spec file, sources, patches, and icons.
--rmsourcespec remove sources and spec file
--recompilesrpm like --rebuild, but don't build any package
------------------------------------------------------------------------------------

To start the build process use the command rpm -b with the spec file as argument. Running rpm -ba will go through all stages and result in a RPM package, a SRPM package, and the software installed in your system (but not entered in the RPM database). If you don't want to go through the whole build process and want to stop at a certain stage, you can give the stage name as additional argument to rpm

If you are only interested in looking at the source code, you can stop at prep stage. The sources are installed, unpacked, and all changes SuSE made to them are applied

Govinda:/usr/src/packages/SPECS # rpm -bp xmms.spec
Executing(%prep): /bin/sh -e /var/tmp/rpm-tmp.69504
+ umask 022
+ cd /usr/src/packages/BUILD
+ cd /usr/src/packages/BUILD
+ rm -rf xmms-1.2.10
+ /bin/gzip -dc /usr/src/packages/SOURCES/xmms-1.2.10.tar.gz
+ tar -xf -
+ STATUS=0
+ '[' 0 -ne 0 ']'
+ cd xmms-1.2.10
++ /usr/bin/id -u
+ '[' 0 = 0 ']'
+ /bin/chown -Rhf root .
++ /usr/bin/id -u
+ '[' 0 = 0 ']'
+ /bin/chgrp -Rhf root .
+ /bin/chmod -Rf a+rX,g-w,o-w .
+ exit 0

First the tar files gets uncompressed and unpacked. If you look into the directory /usr/src/packages/BUILD after you execute the prep stage, you'll see that there is a subdirectory, xmms-1.2.10 containing the source files for the xmms package

Govinda:/usr/src/packages/BUILD/xmms-1.2.10 # ls -l
total 1841
drwxr-xr-x 12 root root 1232 2004-02-23 13:53 .
drwxrwxrwt 3 root root 80 2004-09-28 13:22 ..
-rw-r--r-- 1 root root 9127 2004-01-11 10:22 ABOUT-NLS
-rw-r--r-- 1 root root 2110 2004-01-16 16:41 AUTHORS
-rw-r--r-- 1 root root 17992 2003-05-19 14:22 COPYING
-rw-r--r-- 1 root root 212169 2004-02-23 13:53 ChangeLog
drwxr-xr-x 5 root root 200 2004-02-23 13:53 Effect
-rw-r--r-- 1 root root 6679 2000-12-22 15:09 FAQ
drwxr-xr-x 5 root root 192 2004-02-23 13:53 General
-rw-r--r-- 1 root root 9236 2003-05-19 14:22 INSTALL
drwxr-xr-x 8 root root 256 2004-02-23 13:53 Input
-rw-r--r-- 1 root root 238 2004-01-16 16:11 Makefile.am
-rw-r--r-- 1 root root 24209 2004-02-23 13:44 Makefile.in
-rw-r--r-- 1 root root 8395 2004-02-23 13:49 NEWS
drwxr-xr-x 8 root root 264 2004-02-23 13:53 Output
-rw-r--r-- 1 root root 40371 2004-01-16 16:41 README
....
....

To continue with the example, we'll go on to the compilation stage. You could either start over and let RPM do the preparation again, or use the prepared sources and jump right into the compilation. The default for RPM is to start over at the beginning. The command rpm -bc will have the source and patch files (if any) do the preparation work and then compile the source code. Since we have gone through the preparation already, we will short-circuit RPM and only do the compilation:

Govinda:/usr/src/packages/SPECS # rpm -bc --short-circuit xmms.spec
Executing(%build): /bin/sh -e /var/tmp/rpm-tmp.13688
+ umask 022
+ cd /usr/src/packages/BUILD
+ cd xmms-1.2.10
+ unset LINGUAS
+ CFLAGS=-O2 -march=i486 -mcpu=i686
+ export CFLAGS
+ CXXFLAGS=-O2 -march=i486 -mcpu=i686
+ export CXXFLAGS
+ FFLAGS=-O2 -march=i486 -mcpu=i686
+ export FFLAGS
+ '[' -f configure.in ']'
+ libtoolize --copy --force
You should update your `aclocal.m4' by running aclocal.
+ ./configure i386-pc-linux --prefix=/usr --exec-prefix=/usr --bindir=/usr/bin --sbindir=/usr/sbin --sysconfdir=/etc --datadir=/usr/share --includedir=/usr/include --libdir=/usr/lib --libexecdir=/usr/libexec --localstatedir=/var --sharedstatedir=/usr/com --mandir=/usr/share/man --infodir=/usr/share/info
configure: WARNING: you should use --build, --host, --target
checking build system type... i386-pc-linux
checking host system type... i386-pc-linux
...
...
make[3]: Entering directory `/usr/src/packages/BUILD/xmms-1.2.10/libxmms'
if /bin/sh ./libtool --mode=compile gcc -DHAVE_CONFIG_H -I. -I. -I. -I/usr/include/gtk-1.2 -I/usr/include/glib-1.2 -I/usr/lib/glib/include -D_REENTRANT -I/usr/X11R6/include -I../intl -I.. -O2 -march=i486 -mcpu=i686 -Wall -Wpointer-arith -MT configfile.lo -MD -MP -MF ".deps/configfile.Tpo" -c -o configfile.lo `test -f 'configfile.c' || echo './'`configfile.c; then mv -f ".deps/configfile.Tpo" ".deps/configfile.Plo"; else rm -f ".deps/configfile.Tpo"; exit 1; fi
gcc -DHAVE_CONFIG_H -I. -I. -I. -I/usr/include/gtk-1.2 -I/usr/include/glib-1.2 -I/usr/lib/glib/include -D_REENTRANT -I/usr/X11R6/include -I../intl -I.. -O2 -march=i486 -mcpu=i686 -Wall -Wpointer-arith -MT configfile.lo -MD -MP -MF .deps/configfile.Tpo -c configfile.c -o configfile.o
...
...

After this step the binaries are ready to be installed in your system. You can copy them manually if you are only interested in special parts of the package, or let RPM install the entire set. This is done with rpm -bi. Again, this command by default starts at the very beginning. But we can use the --short-circuit switch again to skip the first two stages:

# rpm -bi --short-circuit xmms.spec
Executing: %install
+ umask 022
+ cd /usr/src/packages/BUILD
+ cd rxvt-2.4.7
+ make install
./autoconf/mkinstalldirs /usr/X11R6/bin
./autoconf/mkinstalldirs /usr/X11R6/man/man1
make[1]: Entering directory `/usr/src/packages/BUILD/xmms-1.2.10/src'
....
....

Besides the missing entry in the RPM database, you now have the same status as you would have with the installed binary package.

The last stage is to create the binary and the source packages. You do this with rpm -ba. Unfortunately there is no way to skip the other stages for this option. So you have to go through the whole process again. The only choice you have is to skip building of the source package. If you want to do this use rpm -bb instead of rpm -ba. In order to have a complete example we will create the binary and the source package:

# rpm -bb xmms.spec
Executing(%prep): /bin/sh -e /var/tmp/rpm-tmp.3103
+ umask 022
+ cd /usr/src/packages/BUILD
+ cd /usr/src/packages/BUILD
+ rm -rf xmms-1.2.10
+ /bin/gzip -dc /usr/src/packages/SOURCES/xmms-1.2.10.tar.gz

...
...
Wrote: /usr/src/packages/SRPMS/xmms-1.2.10.src.rpm
Wrote: /usr/src/packages/RPMS/i386/xmms-1.2.10.i386.rpm

The build process is completed. RPM tells you where it put the source and the binary package

For the impatient
=============
Method# 1:

step (1) Install source rpm

rpm -ivh <application>.src.rpm

This decompresses the source files into /usr/src directory under which the source and spec files (building parameters) are unloaded into the ./SOURCES and ./SPECS directories, respectively.

step (2) cd into /usr/src/SPECS directory and run the following commands in order to build the source according the spec files:

rpm -bb <application>.spec

This compiles the source and packages the binaries into tidy RPM packages for you.

step (3) Install the RPM that you just built:

cd /usr/src/RPMS
rpm -Uvh <application>.i386.rpm

Method# 2:
To compile and install a source RPM package, do the following:
# rpm --rebuild <application>.src.rpm
…
(lots of output)
…
Wrote: /usr/src/packages/RPMS/i386/<application>.i386.rpm
…
+ exit 0
…
If all goes well, you can skip everything below. If not, you may want to cd /usr/src/packages/BUILD/<application>-Version, read on below, and try to figure out how to compile the application