Beyond Linux® From Scratch (System V Edition) - Version 2021-04-13

Chapter 13. Programming

Python-3.9.2

Introduction to Python 3

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

[Note]

Note

Python 3 was installed in LFS. The only reason to rebuild it here is if optional modules are needed.

This package is known to build and work properly using an LFS-10.1 platform.

Package Information

Python 3 Dependencies

Recommended

SQLite-3.35.4 (required if building firefox or thunderbird)

Optional

BlueZ-5.56, GDB-10.1 (required for some tests), Valgrind-3.17.0, and libmpdec

Optional (For Additional Modules)

Berkeley DB-5.3.28 and Tk-8.6.11.1

User Notes: http://wiki.linuxfromscratch.org/blfs/wiki/Python3

Installation of Python 3

Fix a header file, which is needed for some use cases: 

sed 's|cpython/||' -i Include/cpython/pystate.h

Install Python 3 by running the following commands: 

CXX="/usr/bin/g++"              \
./configure --prefix=/usr       \
            --enable-shared     \
            --with-system-expat \
            --with-system-ffi   \
            --with-ensurepip=yes &&
make

To test the result, issue make test. Some tests may need Internet connection.

Now, as the root user: 

make install

Command Explanations

CXX="/usr/bin/g++" ./configure ...: Avoid an annoying message during configuration.

--with-system-expat: This switch enables linking against the system version of Expat.

--with-system-ffi: This switch enables linking against system version of libffi.

--with-ensurepip=yes : This switch enables building pip and setuptools packaging programs. setuptools is needed for building some Python modules.

--with-dbmliborder=bdb:gdbm:ndbm: Use this switch if you want to build Python DBM Module against Berkeley DB instead of GDBM.

--enable-optimization: Use this switch if you want to enable expensive optimizations (i.e. Profile Guided Optimizations). This adds around 20 SBU, but can slightly speed up some uses, such as using Sphinx for creating documentation, or use of Python3 scripts.

--with-lto: This optional switch enables thick Link Time Optimization. Unusually, it creates a much larger /usr/lib/python3.9/config-3.9-<arch>-linux-gnu/libpython3.9.a with a small increase in the time to compile Python. Run-time results do not appear to show any benefit from doing this.

Configuring Python 3

In order for python3 to find the installed documentation, create the following version independent symlink: 

ln -svfn python-3.9.2 /usr/share/doc/python-3

and add the following environment variable to the individual user's or system's profile: 

export PYTHONDOCS=/usr/share/doc/python-3/html

Contents

Installed Programs: 2to3 (symlink) and 2to3-3.9, easy_install-3.9, idle3 (symlink) and idle3.9, pip3 (symlink) and pip3.9, pydoc3 and pydoc3.9, python3 (symlink); python3.9, and python3 (symlink), and python3.9 python3-config (symlink) and python3.9-config
Installed Libraries: libpython3.9.so and libpython3.so
Installed Directories: /usr/include/python3.9, /usr/lib/python3.9, and /usr/share/doc/python-3.9.2

Short Descriptions

easy_install

is a frontend to pip3 to make it easier to configure python modules through the PIP package manager

idle3

is a wrapper script that opens a Python aware GUI editor. For this script to run, you must have installed Tk before Python so that the Tkinter Python module is built

pydoc3

is the Python documentation tool

python3

is an interpreted, interactive, object-oriented programming language

python3.9

is a version-specific name for the python program

Last updated on 2021-03-02 16:19:04 -0600