1. 编译安装 Python

在 CentOS 上因为自带的 Python 版本比较旧，所以要安装高版本的 Python 但同时要求不能影响原来的 python3 命令。

先不急着动手，可以先看看关于多版本的专题。

1.1. 专题: 同系统多版本 Python 问题

非常不建议直接覆盖当前系统的 python 和 python3 命令，Python 每个版本之间多少有点不兼容问题，处理起来非常麻烦，万一系统用到了，就是个大问题。

Building Python: make install can overwrite or masquerade the python3 binary. make altinstall is therefore recommended instead of make install since it only installs exec_prefix/bin/pythonversion.

If you want it to install to, for example, /usr/bin instead of the default (/usr/local/bin in ubuntu/debian), then instead of ./configure, type ./configure --prefix=/usr when told to use it in the guide.

For in your $HOME/bin directory, use --prefix=$HOME.

If it doesn’t exist, add $HOME/bin to your $PATH like this:

$ export PATH=$HOME/bin:$PATH
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This may already be in your .bashrc in ubuntu, and others. If it is, when you next log in, $HOME/bin will be added to your $PATH automatically.

1.1.1. altinstall bininstall maninstall

Let’s take a look at the generated Makefile!

First, the install target:

install:         altinstall bininstall maninstall
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It does everything altinstall does, along with bininstall and maninstall

Here’s bininstall; it just creates the python and other symbolic links.

# Install the interpreter by creating a symlink chain:
#  $(PYTHON) -> python2 -> python$(VERSION))
# Also create equivalent chains for other installed files
bininstall:     altbininstall
        -if test -f $(DESTDIR)$(BINDIR)/$(PYTHON) -o -h $(DESTDIR)$(BINDIR)/$(PYTHON); \
        then rm -f $(DESTDIR)$(BINDIR)/$(PYTHON); \
        else true; \
        fi
        (cd $(DESTDIR)$(BINDIR); $(LN) -s python2$(EXE) $(PYTHON))
        -rm -f $(DESTDIR)$(BINDIR)/python2$(EXE)
        (cd $(DESTDIR)$(BINDIR); $(LN) -s python$(VERSION)$(EXE) python2$(EXE))
        ... (More links created)
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And here’s maninstall, it just creates “unversioned” links to the Python manual pages.

# Install the unversioned manual pages
maninstall:     altmaninstall
        -rm -f $(DESTDIR)$(MANDIR)/man1/python2.1
        (cd $(DESTDIR)$(MANDIR)/man1; $(LN) -s python$(VERSION).1 python2.1)
        -rm -f $(DESTDIR)$(MANDIR)/man1/python.1
        (cd $(DESTDIR)$(MANDIR)/man1; $(LN) -s python2.1 python.1)
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TLDR: altinstall skips creating the python link and the manual pages links, install will hide the system binaries and manual pages.

1.1.2. 兼容性修正

1.1.2.1. Redhat/CentOS 系

一般在 /usr/bin/ 下放一个链接，链接到 /usr/local/bin/ 下面:

$ ln -s /usr/local/bin/pip    /usr/bin/pip
$ ln -s /usr/local/bin/pip3   /usr/bin/pip3
$ ln -s /usr/local/bin/pip3.9 /usr/local/bin/pip3
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1.1.2.2. Debian/Ubuntu 系

1.1.3. 快速虚拟化环境工具

• virtualenv
• venv

1.2. Step 1: Install Python Dependencies

Login to your CentOS 8 / CentOS 7 system as root or user with sudo privileges.

Then do system update

sudo yum -y install epel-release
sudo yum -y update
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Reboot after the upgrade before you continue to install dependencies

sudo reboot
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Install required software development tools required to build Python 3.9 on CentOS 8 / CentOS 7:

sudo yum groupinstall "Development Tools" -y
sudo yum install openssl-devel libffi-devel bzip2-devel -y
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Confirm gcc is available:

$ gcc --version
gcc (GCC) 8.5.0 20210514 (Red Hat 8.5.0-4)
Copyright (C) 2018 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
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1.3. Step 2: Download latest Python 3.9 Archive

Ensure wget is installed:

sudo yum install wget -y
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Use wget to download the latest Python 3.9 release.

wget https://www.python.org/ftp/python/3.9.10/Python-3.9.10.tgz
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Extract the archive file using tar:

tar xvf Python-3.9.10.tgz
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Switch to the directory created from the file extraction:

cd Python-3.9*/
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1.4. Step 3: Install Python 3.9 on CentOS 8 / CentOS 7

Run the command below to configure Python installation.

./configure --enable-optimizations
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Build Python 3.9 on CentOS 8 / CentOS 7:

sudo make altinstall # altinstall is important, DO NOT use `make install`.
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Python 安装时 make install 和 make altinstall 的区别: altinstall skips creating the python link and the manual pages links. altinstall 跳过创建 Python 链接和手册页链接的操作。如果使用 make install，在系统中将会有两个不同版本的 Python 在 /usr/bin 目录中，这将会导致很多问题。

Be patient as this takes quite some time depending on number of CPU cores in your system.

Check Python 3.9 installation on CentOS 8 / CentOS 7. Run below command to confirm successful installation of Python 3.9 on CentOS 8 / CentOS 7:

$ python3.9 --version
Python 3.9.10
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Pip3.9 must have been installed as well:

$ pip3.9 --version
pip 21.2.4 from /usr/local/lib/python3.9/site-packages/pip (python 3.9)
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Upgrade pip

$ /usr/local/bin/python3.9 -m pip install --upgrade pip
$ pip3.9 --version
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