Packaging and distributing software

Procedure

1. Back up the original source code:

   $ cp -p cello.c cello.c.orig

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   The -p option preserves mode, ownership, and timestamps.

2. Modify cello.c as needed:

   #include <stdio.h>
   
   int main(void) {
       printf("Hello World from my very first patch!\n");
       return 0;
   }

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3. 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

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   Lines that start with + replace the lines that start with -.

   Note

   Using the Naur options with the diff 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, the diff 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 the diff utility found.

   However, note that in this particular case, only the -u option is necessary.

4. Save the patch to a file:

   $ diff -Naur cello.c.orig cello.c > cello.patch

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5. Restore the original cello.c:

   $ mv cello.c.orig cello.c

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   Important

   You 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.

1. Redirect the patch file to the patch command:

   $ patch < cello.patch
   patching file cello.c

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2. 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;
   }

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Verification

1. Build the patched cello.c program:

   $ make
   gcc -g -o cello cello.c

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2. Run the built cello.c program:

   $ ./cello
   Hello World from my very first patch!

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Procedure

1. Move all required files into a single directory:

   $ mkdir bello-0.1
   
   $ mv bello bello-0.1/
   
   $ mv LICENSE bello-0.1/

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2. 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

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3. Move the created archive to the ~/rpmbuild/SOURCES/ directory, which is the default directory where the rpmbuild command stores the files for building packages:

   $ mv bello-0.1.tar.gz ~/rpmbuild/SOURCES/

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Procedure

1. 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/

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2. 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

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3. Move the created archive to the ~/rpmbuild/SOURCES/ directory, which is the default directory where the rpmbuild command stores the files for building packages:

   $ mv cello-1.0.tar.gz ~/rpmbuild/SOURCES/

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Procedure

1. Navigate to the ~/rpmbuild/SPECS directory:

   $ cd ~/rpmbuild/SPECS

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2. Create a spec file for each of the three implementations of the Hello World! program:

   $ rpmdev-newspec bello
   bello.spec created; type minimal, rpm version >= 4.11.
   
   $ rpmdev-newspec cello
   cello.spec created; type minimal, rpm version >= 4.11.
   
   $ rpmdev-newspec python-pello
   python-pello.spec created; type minimal, rpm version >= 4.11.

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   Important

   When packaging a Python project into RPM, always add the python- prefix to the original name of the project. The project name here is Pello and, therefore, the name of the spec is python-pello.

   The ~/rpmbuild/SPECS/ directory now contains three spec files named bello.spec, cello.spec, and python-pello.spec.

3. Examine the created files.

   The directives in the files represent those described in About spec files. In the following sections, you will populate particular section in the output files of rpmdev-newspec.

Procedure

1. Open the ~/rpmbuild/SPECS/<name>.spec file provided by the rpmdev-newspec utility.

2. Populate the following directives of the spec file Preamble section:

   Name

   Name was already specified as an argument to rpmdev-newspec.

   Version

   Set Version to match the upstream release version of the source code.

   Release

   Release is automatically set to 1%{?dist}, which is initially 1.

   Summary

   Enter a one-line explanation of the package.

   License

   Enter the software license associated with the source code.

   URL

   Enter the URL to the upstream software website. For consistency, utilize the %{name} RPM macro variable and use the https://example.com/%{name} format.

   Source

   Enter the URL to the upstream software source code. Link directly to the software version being packaged.

   Note

   The example URLs in this documentation include hard-coded values that could possibly change in the future. Similarly, the release version can change as well. To simplify these potential future changes, use the %{name} and %{version} macros. By using these macros, you need to update only one field in the spec file.

   BuildRequires

   Specify build-time dependencies for the package.

   Requires

   Specify run-time dependencies for the package.

   BuildArch

   Specify the software architecture.

3. Populate the following directives of the spec file Body section. You can think of these directives as section headings, because these directives can define multi-line, multi-instruction, or scripted tasks to occur.

   %description

   Enter the full description of the software.

   %prep

   Enter a command or series of commands to prepare software for building.

   %build

   Enter a command or series of commands for building software.

   %install

   Enter a command or series of commands that instruct the rpmbuild command on how to install the software into the BUILDROOT directory.

   %files

   Specify the list of files, provided by the RPM package, to be installed on your system.

   %changelog

   Enter the list of datestamped entries for each Version-Release of the package.

   Start the first line of the %changelog section with an asterisk (*) character followed by Day-of-Week Month Day Year Name Surname <email> - Version-Release.

   For the actual change entry, follow these rules:

   • Each change entry can contain multiple items, one for each change.
   • Each item starts on a new line.
   • Each item begins with a hyphen (-) character.

Procedure

1. Navigate to the ~/rpmbuild/SPECS/ directive, which contains the created spec file:

   $ cd ~/rpmbuild/SPECS/

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2. Build the source RPM by entering the rpmbuild command with the specified spec file:

   $ rpmbuild -bs <specfile>

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   The -bs option stands for build source.

   For example, to build source RPMs for the bello, pello, and cello programs, enter:

   $ rpmbuild -bs bello.spec
   Wrote: /home/admiller/rpmbuild/SRPMS/bello-0.1-1.el9.src.rpm
   
   $ rpmbuild -bs python-pello.spec
   Wrote: /home/admiller/rpmbuild/SRPMS/python-pello-1.0.2-1.el9.src.rpm
   
   $ rpmbuild -bs cello.spec
   Wrote: /home/admiller/rpmbuild/SRPMS/cello-1.0-1.el9.src.rpm

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Procedure

1. Navigate to the ~/rpmbuild/SRPMS/ directive, which contains the source RPM:

   $ cd ~/rpmbuild/SRPMS/

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2. Rebuild the binary RPM from the source RPM:

   $ rpmbuild --rebuild <srpm>

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   For example, to rebuild bello, pello, and cello from their SRPMs, enter:

   $ rpmbuild --rebuild bello-0.1-1.el9.src.rpm
   [output truncated]
   
   $ rpmbuild --rebuild python-pello-1.0.2-1.el9.src.rpm
   [output truncated]
   
   $ rpmbuild --rebuild cello-1.0-1.el9.src.rpm
   [output truncated]

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Procedure

1. Navigate to the ~/rpmbuild/SPECS/ directive, which contains spec files:

   $ cd ~/rpmbuild/SPECS/

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2. Build the binary RPM from its spec:

   $ rpmbuild -bb <spec_file>

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   For example, to build bello, pello, and cello binary RPMs from their spec files, enter:

   $ rpmbuild -bb bello.spec
   
   $ rpmbuild -bb python-pello.spec
   
   $ rpmbuild -bb cello.spec

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Procedure

1. Generate a GPG key pair:

   # gpg --gen-key

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2. Check the generated key pair:

   # gpg --list-keys

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3. Export the public key:

   # gpg --export -a '<Key_name>' > RPM-GPG-KEY-pmanager

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   Replace <Key_name> with the real key name that you have selected.

4. Import the exported public key into an RPM database:

   # rpm --import RPM-GPG-KEY-pmanager

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Procedure

1. To display all built-in RPM macros, run:

   rpm --showrc

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   Note

   The output is quite sizeable. To narrow the result, use the command above with the grep command.

2. To find information about the RPMs macros for your system’s version of RPM, run:

   rpm -ql rpm

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   Note

   RPM macros are the files titled macros in the output directory structure.

Procedure

1. Open the pello.spec file.

2. Find the following line:

   install -m 0644 %{name}.py* %{buildroot}/usr/lib/%{name}/

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3. Under the above line, insert:

   %post -p /usr/bin/python3
   print("This is {} code".format("python"))

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4. Build your package as described in Building RPMs.

5. Install your package:

   # dnf install /home/<username>/rpmbuild/RPMS/noarch/pello-0.1.2-1.el9.noarch.rpm

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6. Check the output message after the installation:

   Installing       : pello-0.1.2-1.el9.noarch                              1/1
   Running scriptlet: pello-0.1.2-1.el9.noarch                              1/1
   This is python code

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Procedure

1. Make sure that one of the following directories containing upstream-provided metadata is included in the resulting RPM:

   • .dist-info

   • .egg-info

     The RPM build process automatically generates virtual pythonX.Ydist provides from these directories, for example:

     python3.9dist(pello)

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     The Python dependency generator then reads the upstream metadata and generates runtime requirements for each RPM package using the generated pythonX.Ydist virtual provides. For example, a generated requirements tag might look as follows:

     Requires: python3.9dist(requests)

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2. Inspect the generated requires.

3. To remove some of the generated requires, use one of the following approaches:

   1. Modify the upstream-provided metadata in the %prep section of the SPEC file.
   2. Use automatic filtering of dependencies described in the upstream documentation.
4. To disable the automatic dependency generator, include the %{?python_disable_dependency_generator} macro above the main package’s %description declaration.