Linux From Scratch (w/Pacman) - Version r12.3-6-wip

Chapter 7. Entering Chroot and Building Additional Temporary Tools

7.29. Python-3.13.2

The Python 3 package contains the Python development environment. It is useful for object-oriented programming, writing scripts, prototyping large programs, or developing entire applications.

Approximate build time: 2.1 SBU
Required disk space: 501 MB

7.29.1. Reinstallation of Python 3

Prepare Python for compilation: 

./configure --prefix=/usr        \
            --enable-shared      \
            --with-system-expat  \
            --with-system-ffi    \
            --enable-optimizations

The meaning of the configure options:

--with-system-expat

This switch enables linking against system version of Expat.

--with-system-ffi

This switch enables linking against system version of libffi.

--enable-optimizations

This switch enables stable, but expensive, optimizations.

Compile the package: 

make

Running the tests at this point is not recommended. The tests are known to hang indefinitely in the partial LFS environment. If desired, the tests can be rerun at the end of this chapter or when Python 3 is reinstalled in BLFS. To run the tests anyway, issue make test.

Install the package: 

make install

We use the pip3 command to install Python 3 programs and modules for all users as root in several places in this book. This conflicts with the Python developers' recommendation: to install packages into a virtual environment, or into the home directory of a regular user (by running pip3 as this user). A multi-line warning is triggered whenever pip3 is issued by the root user.

The main reason for the recommendation is to avoid conflicts with the system's package manager (dpkg, for example). LFS does not have a system-wide package manager, so this is not a problem. Also, pip3 will check for a new version of itself whenever it's run. Since domain name resolution is not yet configured in the LFS chroot environment, pip3 cannot check for a new version of itself, and will produce a warning.

After we boot the LFS system and set up a network connection, a different warning will be issued, telling the user to update pip3 from a pre-built wheel on PyPI (whenever a new version is available). But LFS considers pip3 to be a part of Python 3, so it should not be updated separately. Also, an update from a pre-built wheel would deviate from our objective: to build a Linux system from source code. So the warning about a new version of pip3 should be ignored as well. If you wish, you can suppress all these warnings by running the following command, which creates a configuration file: 

cat > /etc/pip.conf << EOF
[global]
root-user-action = ignore
disable-pip-version-check = true
EOF