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<TITLE>Maximum RPM (RPM):Miscellanea:EarthWeb Inc.-</TITLE>
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<!-- TITLE=Maximum RPM (RPM)//-->
<!-- AUTHOR=Edward Bailey//-->
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<A NAME="PAGENUM-108"><P>Page 108</P></A>
<P>Let's try the file command on this mystery file to see what we can find out about it:
</P>
<!-- CODE SNIP //-->
<PRE>
# file etcskel-1.0-3.src.rpm
etcskel-1.0-3.src.rpm: RPM v2 src i386 etcskel-1.0-3
#
</PRE>
<!-- END CODE SNIP //-->
<P>Well, it's a package file all, right—for version 1.0, release 3 of the
etcskel package. It's in RPM version 2 format and built for Intel-based systems. But what does the
src mean?
</P>
<H4><A NAME="ch08_ 13">
8.3.1. A Gentle Introduction to Source Code
</A></H4>
<P>This package file contains not the executable, or
binary, files that a normal package contains, but rather the source files required to create those binaries. When a programmer creates a
new program, he writes the instructions, often called
code, in one or more files. The source code is then compiled into a binary that can be executed by the computer.
</P>
<P>As part of the process of building package files (a process covered in great detail in Part II),
two types of package files are created:
</P>
<UL>
<LI> The binary,
or executable, package file
<LI> The source package file
</UL>
<P>The source package contains everything needed to re-create not only the programs and
associated files that are contained in the binary package file, but the binary and source package
files themselves.
</P>
<H4><A NAME="ch08_ 14">
8.3.2. Do You Really Need More Information Than This?
</A></H4>
<P>The following discussion is going to get rather technical. Unless you're the type of person
who likes to modify other people's code, chances are you won't need much more information
than this. But if you're still interested, let's explore further.
</P>
<H4><A NAME="ch08_ 15">
8.3.3. So What Can I Do with It?
</A></H4>
<P>One thing you can do with source package files is install them. Let's try an install of a
source package:
</P>
<!-- CODE SNIP //-->
<PRE>
# rpm -i cdp-0.33-3.src.rpm
#
</PRE>
<!-- END CODE SNIP //-->
<P>Well, that doesn't tell us very much and (take our word for it) adding
-v doesn't improve the situation appreciably. Let's haul out the big guns and try
-vv:
</P>
<!-- CODE //-->
<PRE>
# rpm -ivv cdp-0.33-3.src.rpm
D: installing cdp-0.33-3.src.rpm
Installing cdp-0.33-3.src.rpm
D: package is a source package major = 2
D: installing a source package
D: sources in: ///usr/src/redhat/SOURCES
</PRE>
<!-- END CODE //-->
<A NAME="PAGENUM-109"><P>Page 109</P></A>
<!-- CODE //-->
<PRE>
D: spec file in: ///usr/src/redhat/SPECS
D: file "cdp-0.33-cdplay.patch" complete
D: file "cdp-0.33-fsstnd.patch" complete
D: file "cdp-0.33.spec" complete
D: file "cdp-0.33.tgz" complete
D: renaming ///usr/src/redhat/SOURCES/cdp-0.33.spec
to
///usr/src/redhat/SPECS/cdp-0.33.spec
#
</PRE>
<!-- END CODE //-->
<P>What does this output say? Well, RPM recognizes that the file is a source package. It
mentions that sources (we know what they are) are in
/usr/src/redhat/SOURCES. Let's take a look:
</P>
<!-- CODE //-->
<PRE>
# ls -al /usr/src/redhat/SOURCES/
-rw-rw-r-- 1 root root 364 Apr 24 22:35 cdp-0.33-cdplay.patch
-rw-r--r-- 1 root root 916 Jan 8 12:07 cdp-0.33-fsstnd.patch
-rw-r--r-- 1 root root 148916 Nov 10 1995 cdp-0.33.tgz
#
</PRE>
<!-- END CODE //-->
<P>Some files there seem to be related to cdp. The two files ending with
.patch are patches to the source. RPM permits patches to be processed when building binary packages. The patches
are bundled along with the original, unmodified sources in the source package.
</P>
<P>The last file is a gzipped tar file. If you've gotten software off the Internet, you're
probably familiar with tar files, gzipped or not. If we look inside the file, we should see all the
usual kinds of things: readme files, a makefile or two, and some source code:
</P>
<!-- CODE //-->
<PRE>
# tar ztf cdp-0.33.tgz
cdp-0.33/COPYING
cdp-0.33/ChangeLog
cdp-0.33/INSTALL
cdp-0.33/Makefile
cdp-0.33/README
cdp-0.33/cdp
cdp-0.33/cdp-0.33.lsm
cdp-0.33/cdp.1
cdp-0.33/cdp.1.Z
cdp-0.33/cdp.c
cdp-0.33/cdp.h
. . .
#
</PRE>
<!-- END CODE //-->
<P>There's more, but you get the idea. Okay, so there are the sources. But what is that spec
file mentioned in the output? It mentions something about
/usr/src/redhat/SPECS, so let's see what we have in that directory:
</P>
<!-- CODE SNIP //-->
<PRE>
# ls -al /usr/src/redhat/SPECS
-rw-r--r-- 1 root root 397 Apr 24 22:36 cdp-0.33.spec
</PRE>
<!-- END CODE SNIP //-->
<P>Without making a long story too short, a spec file contains information used by RPM to
create the binary and source packages. Using the spec file, RPM does the following:
</P>
<OL>
<LI> Unpacks the sources.
<LI> Applies patches (if any exist).
</OL>
<A NAME="PAGENUM-110"><P>Page 110</P></A>
<OL START=3>
<LI> Builds the software.
<LI> Creates the binary package file.
<LI> Creates the source package file.
<LI> Cleans up after itself.
</OL>
<P>The neatest part of this is that RPM does all this automatically, under the control of the
spec file. That's about all we're going to say about how RPM builds packages. For more
information, please see Part II.
</P>
<H4><A NAME="ch08_ 16">
8.3.4. Stick with Us!
</A></H4>
<P>As noted several times, we'll be covering the subject of building packages with RPM in Part
II. Be forewarned, however: Package building, while straightforward, is not a task for people
new to programming. But if you've written a program or two, you'll probably find RPM's
package building a piece of cake.
</P>
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