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<TITLE>Maximum RPM (RPM):Inside the Spec File:EarthWeb Inc.-</TITLE>
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<!-- ISBN=0672311054 //-->
<!-- TITLE=Maximum RPM (RPM)//-->
<!-- AUTHOR=Edward Bailey//-->
<!-- PUBLISHER=Macmillan Computer Publishing//-->
<!-- IMPRINT=Sams//-->
<!-- CHAPTER=13 //-->
<!-- PAGES=0163-0204 //-->
<!-- UNASSIGNED1 //-->
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<A NAME="PAGENUM-176"><P>Page 176</P></A>
<B>
13.2.6.2. The nosource Tag
</B>
<P>The nosource tag is used to direct RPM to omit one or more source files from the source
package. Why would someone want to go to the trouble of specifying a source file, only to
exclude it? The reasons for this can be varied, but let's look at one example: The software known
as pretty good privacy, or PGP.
</P>
<P>PGP contains encryption routines of such high quality that the U.S. government restricts
their export. (There is also an international version that may be used in non-U.S. countries.
See Appendix G, "An Introduction to PGP.") While it would be nice to create a PGP package
file, the resulting package could not legally be transferred between the U.S. and other countries.
</P>
<P>However, what if all files other than the original source were packaged using RPM? Well,
a binary package made without PGP would be of little use, but what about the source
package? It would contain the spec file, maybe some patches, and perhaps even an icon file. Since
the controversial PGP software was not a part of the source package, this sanitized source
package could be downloaded legally in any country. The person who downloaded a copy could
then go about legally obtaining the PGP sources himself, place them in RPM's
SOURCES directory, and create a binary package. He wouldn't even need to change the
nosource tag. One rpm -ba command later, and the user would have a perfectly usable PGP binary package file.
</P>
<P>Since there may be more than one source tag in a spec file, the format of the
nosource tag is as follows:
</P>
<!-- CODE SNIP //-->
<PRE>
nosource: <src-num>, <src-num>...<src-num>
</PRE>
<!-- END CODE SNIP //-->
<P><src-num> represents the number following the source tag. If there is more than one number
in the list, the numbers may be separated by either commas or spaces. For example, consider
a package containing the following source tags:
</P>
<!-- CODE SNIP //-->
<PRE>
source: blather-4.5.tar.gz
Source1: bother-1.2.tar.gz
source2: blather-lib-4.5.tar.gz
source3: bother-lib-1.2.tar.gz
</PRE>
<!-- END CODE SNIP //-->
<P>If the source files for blather and blather-lib were not to be included in the package,
the following nosource line could be added:
</P>
<!-- CODE SNIP //-->
<PRE>
NoSource: 0, 3
</PRE>
<!-- END CODE SNIP //-->
<P>What about that 0? Keep in mind that the first unnumbered source tag in a spec file is
automatically numbered 0 by RPM.
</P>
<B>
13.2.6.3. The patch Tag
</B>
<P>The patch tag is used to identify which patches are associated with the software
being packaged. The patch files are kept in RPM's
SOURCES directory, so only the name of the patch
file should be specified. Here is an example:
</P>
<!-- CODE SNIP //-->
<PRE>
Patch: cdp-0.33-fsstnd.patch
</PRE>
<!-- END CODE SNIP //-->
<A NAME="PAGENUM-177"><P>Page 177</P></A>
<P>There are no hard-and-fast requirements for naming the patch files, but traditionally the
filename starts with the software name and version, separated by dashes. The next part of the patch
file name usually includes one or more words indicating the reason for the patch. In the
preceding example, the patch file contains changes necessary to bring the software into compliance
with the Linux File System Standard, hence the
fsstnd magic incantation.
</P>
<P>RPM processes patch tags the same way it does
source tags. Therefore, it's acceptable to use a URL on a
patch line, too.
</P>
<P>A spec file may contain more than one patch tag. This is necessary for those cases where
the software being packaged requires more than one patch. However, the
patch tags must be uniquely identified. This is done by appending a number to the end of the tag itself. In fact, RPM
does this internally for the first patch tag in a spec file, in essence turning it into
patch0. Therefore, if a package contains three patches, this method of specifying them:
</P>
<!-- CODE SNIP //-->
<PRE>
Patch: blather-4.5-bugfix.patch
Patch1: blather-4.5-config.patch
Patch2: blather-4.5-somethingelse.patch
</PRE>
<!-- END CODE SNIP //-->
<P>is equivalent to this one:
</P>
<!-- CODE SNIP //-->
<PRE>
Patch0: blather-4.5-bugfix.patch
Patch1: blather-4.5-config.patch
Patch2: blather-4.5-somethingelse.patch
</PRE>
<!-- END CODE SNIP //-->
<P>Either approach may be used, but the second method looks nicer.
</P>
<B>
13.2.6.4. The nopatch Tag
</B>
<P>The nopatch tag is similar to the nosource tag discussed
earlier. Just like the nosource tag, the nopatch tag is used to direct RPM
to omit something from the source package. In the case
of nosource, that something was one or more sources. For the
nopatch tag, the something is one or more patches.
</P>
<P>Since each patch tag in a spec file must be numbered, the
nopatch tag uses those numbers to specify which patches are not to be included in the package. The
nopatch tag is used in this manner:
</P>
<!-- CODE SNIP //-->
<PRE>
NoPatch: 2 3
</PRE>
<!-- END CODE SNIP //-->
<P>In this example, the source files specified on the
source2 and source3 lines are not to be included in the build.
</P>
<P>This concludes our study of RPM's tags. In the next section, we'll look at the various
scripts that RPM uses to build, as well as to install and erase, packages.
</P>
<A NAME="PAGENUM-178"><P>Page 178</P></A>
<H3>
13.3. Scripts: RPM's Workhorse
</H3>
<P>The scripts that RPM uses to control the build process are among the most varied and
interesting parts of the spec file. Many spec files also contain scripts that perform a variety of
tasks whenever the package is installed or erased.
</P>
<P>The start of each script is denoted by a keyword. For example, the
%build keyword marks the start of the script RPM will execute when building the software to be packaged. Note that,
in the strictest sense of the word, these parts of the spec file are not scripts. For example, they
do not start with the traditional invocation of a shell. However, the contents of each script
section are copied into a file and executed by RPM as a full-fledged script. This is part of the power
of RPM: Anything that can be done in a script can be done by RPM.
</P>
<P>Let's start by looking at the scripts used during the build process.
</P>
<H4><A NAME="ch13_ 6">
13.3.1. Build-Time Scripts
</A></H4>
<P>The scripts that RPM uses during the building of a package follow the steps known to
every software developer:
</P>
<OL>
<LI> Unpack the sources.
<LI> Build the software.
<LI> Install the software.
<LI> Clean up.
</OL>
<P>Although each of the scripts performs a specific function in the build process, they share a
common environment. Using RPM's --test option (described in section 12.1.11 in Chapter
12), we can see the common portion of each script. In the following example, we've taken the
cdplayer package, issued an rpm -ba --test
cdplayer-1.0-1.spec, and viewed the script files left
in RPM's temporary directory. This section (with the appropriate package-specific values) is
present in every script RPM executes during a build:
</P>
<!-- CODE //-->
<PRE>
#!/bin/sh -e
# Script generated by rpm
RPM_SOURCE_DIR="/usr/src/redhat/SOURCES"
RPM_BUILD_DIR="/usr/src/redhat/BUILD"
RPM_DOC_DIR="/usr/doc"
RPM_OPT_FLAGS="-O2 -m486 -fno-strength-reduce"
RPM_ARCH="i386"
RPM_OS="Linux"
RPM_ROOT_DIR="/tmp/cdplayer"
RPM_BUILD_ROOT="/tmp/cdplayer"
RPM_PACKAGE_NAME="cdplayer"
RPM_PACKAGE_VERSION="1.0"
RPM_PACKAGE_RELEASE="1"
set -x
umask 022
</PRE>
<!-- END CODE //-->
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