Chapter 3. Preparing software for RPM packaging
To prepare a piece of software for packaging with RPM, you can first patch the software, create a LICENSE file for it, and archive it as a tarball.
3.1. Patching software
When packaging software, you might need to make certain changes to the original source code, such as fixing a bug or changing a configuration file. In RPM packaging, you can instead leave the original source code intact and apply patches on it.
A patch is a piece of text that updates a source code file. The patch has a diff format, because it represents the difference between two versions of the text. You can create a patch by using the diff
utility, and then apply the patch to the source code by using the patch utility.
Software developers often use Version Control Systems such as Git to manage their code base. Such tools offer their own methods of creating diffs or patching software.
3.1.1. Creating a patch file for a sample C program
You can create a patch from the original source code by using the diff
utility. For example, to patch a Hello world
program written in C (cello.c
), complete the following steps.
Prerequisites
You installed the
diff
utility on your system:# yum install diffutils
Procedure
Back up the original source code:
$ cp -p cello.c cello.c.orig
The
-p
option preserves mode, ownership, and timestamps.Modify
cello.c
as needed:#include <stdio.h> int main(void) { printf("Hello World from my very first patch!\n"); return 0; }
Generate a patch:
$ diff -Naur cello.c.orig cello.c --- cello.c.orig 2016-05-26 17:21:30.478523360 -0500 + cello.c 2016-05-27 14:53:20.668588245 -0500 @@ -1,6 +1,6 @@ #include<stdio.h> int main(void){ - printf("Hello World!\n"); + printf("Hello World from my very first patch!\n"); return 0; } \ No newline at end of file
Lines that start with
+
replace the lines that start with-
.NoteUsing the
Naur
options with thediff
command is recommended because it fits the majority of use cases:-N
(--new-file
)The
-N
option handles absent files as empty files.-a
(--text
)The
-a
option treats all files as text. As a result, thediff
utility does not ignore the files it classified as binaries.-u
(-U NUM
or--unified[=NUM]
)The
-u
option returns output in the form of output NUM (default 3) lines of unified context. This is a compact and an easily readable format commonly used in patch files.-r
(--recursive
)The
-r
option recursively compares any subdirectories that thediff
utility found.
However, note that in this particular case, only the
-u
option is necessary.Save the patch to a file:
$ diff -Naur cello.c.orig cello.c > cello.patch
Restore the original
cello.c
:$ mv cello.c.orig cello.c
ImportantYou must retain the original
cello.c
because the RPM package manager uses the original file, not the modified one, when building an RPM package. For more information, see Working with spec files.
Additional resources
-
diff(1)
man page
3.1.2. Patching a sample C program
To apply code patches on your software, you can use the patch
utility.
Prerequisites
You installed the
patch
utility on your system:# yum install patch
- You created a patch from the original source code. For instructions, see Creating a patch file for a sample C program.
Procedure
The following steps apply a previously created cello.patch
file on the cello.c
file.
Redirect the patch file to the
patch
command:$ patch < cello.patch patching file cello.c
Check that the contents of
cello.c
now reflect the desired change:$ cat cello.c #include<stdio.h> int main(void){ printf("Hello World from my very first patch!\n"); return 1; }
Verification
Build the patched
cello.c
program:$ make gcc -g -o cello cello.c
Run the built
cello.c
program:$ ./cello Hello World from my very first patch!
3.2. Creating a LICENSE file
It is recommended that you distribute your software with a software license.
A software license file informs users of what they can and cannot do with a source code. Having no license for your source code means that you retain all rights to this code and no one can reproduce, distribute, or create derivative works from your source code.
Procedure
Create the
LICENSE
file with the required license statement:$ vim LICENSE
Example 3.1. Example GPLv3
LICENSE
file text$ cat /tmp/LICENSE This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with this program. If not, see http://www.gnu.org/licenses/.
Additional resources
3.3. Creating a source code archive for distribution
An archive file is a file with the .tar.gz
or .tgz
suffix. Putting source code into the archive is a common way to release the software to be later packaged for distribution.
3.3.1. Creating a source code archive for a sample Bash program
The bello project is a Hello World
file in Bash.
The following example contains only the bello
shell script. Therefore, the resulting tar.gz
archive has only one file in addition to the LICENSE
file.
The patch
file is not distributed in the archive with the program. The RPM package manager applies the patch when the RPM is built. The patch will be placed into the ~/rpmbuild/SOURCES/
directory together with the tar.gz
archive.
Prerequisites
-
Assume that the
0.1
version of thebello
program is used. -
You created a
LICENSE
file. For instructions, see Creating a LICENSE file.
Procedure
Move all required files into a single directory:
$ mkdir bello-0.1 $ mv ~/bello bello-0.1/ $ mv LICENSE bello-0.1/
Create the archive for distribution:
$ tar -cvzf bello-0.1.tar.gz bello-0.1 bello-0.1/ bello-0.1/LICENSE bello-0.1/bello
Move the created archive to the
~/rpmbuild/SOURCES/
directory, which is the default directory where therpmbuild
command stores the files for building packages:$ mv bello-0.1.tar.gz ~/rpmbuild/SOURCES/
Additional resources
3.3.2. Creating a source code archive for a sample Python program
The pello project is a Hello World
file in Python.
The following example contains only the pello.py
program. Therefore, the resulting tar.gz
archive has only one file in addition to the LICENSE
file.
The patch
file is not distributed in the archive with the program. The RPM package manager applies the patch when the RPM is built. The patch will be placed into the ~/rpmbuild/SOURCES/
directory together with the tar.gz
archive.
Prerequisites
-
Assume that the
0.1.1
version of thepello
program is used. -
You created a
LICENSE
file. For instructions, see Creating a LICENSE file.
Procedure
Move all required files into a single directory:
$ mkdir pello-0.1.1 $ mv pello.py pello-0.1.1/ $ mv LICENSE pello-0.1.1/
Create the archive for distribution:
$ tar -cvzf pello-0.1.1.tar.gz pello-0.1.1 pello-0.1.1/ pello-0.1.1/LICENSE pello-0.1.1/pello.py
Move the created archive to the
~/rpmbuild/SOURCES/
directory, which is the default directory where therpmbuild
command stores the files for building packages:$ mv pello-0.1.1.tar.gz ~/rpmbuild/SOURCES/
Additional resources
3.3.3. Creating a source code archive for a sample C program
The cello project is a Hello World
file in C.
The following example contains only the cello.c
and the Makefile
files. Therefore, the resulting tar.gz
archive has two files in addition to the LICENSE
file.
The patch
file is not distributed in the archive with the program. The RPM package manager applies the patch when the RPM is built. The patch will be placed into the ~/rpmbuild/SOURCES/
directory together with the tar.gz
archive.
Prerequisites
-
Assume that the
1.0
version of thecello
program is used. -
You created a
LICENSE
file. For instructions, see Creating a LICENSE file.
Procedure
Move all required files into a single directory:
$ mkdir cello-1.0 $ mv cello.c cello-1.0/ $ mv Makefile cello-1.0/ $ mv LICENSE cello-1.0/
Create the archive for distribution:
$ tar -cvzf cello-1.0.tar.gz cello-1.0 cello-1.0/ cello-1.0/Makefile cello-1.0/cello.c cello-1.0/LICENSE
Move the created archive to the
~/rpmbuild/SOURCES/
directory, which is the default directory where therpmbuild
command stores the files for building packages:$ mv cello-1.0.tar.gz ~/rpmbuild/SOURCES/
Additional resources