在不破坏yum的情况下升级python

Question

我最近通过从源代码编译在CentOS机器上安装了Python 2.7.3。Python 2.7.3安装在/opt/python2.7上，当我安装它时，我只需更改/usr/bin/Python以指向新版本。这显然是错误的，因为当我这样做的时候，它打破了百胜。我会得到以下内容。

There was a problem importing one of the Python modules
required to run yum. The error leading to this problem was:

   No module named yum

Please install a package which provides this module, or
verify that the module is installed correctly.

It's possible that the above module doesn't match the
current version of Python, which is:
2.7.3 (default, May 15 2012, 17:45:42) 
[GCC 4.4.4 20100726 (Red Hat 4.4.4-13)]

If you cannot solve this problem yourself, please go to 
the yum faq at:
  http://yum.baseurl.org/wiki/Faq

我更改了/usr/bin/python以指向python 2.6.6，但现在2.6.6是python的默认版本。你知道怎么解决这个问题吗？

Answer 1

我已经编写了一个关于如何在Centos6和Centos7上安装最新版本的Python 2和Python 3的快速指南。它目前涵盖了Python 2.7.13和Python 3.6.0：

# Start by making sure your system is up-to-date:
yum update
# Compilers and related tools:
yum groupinstall -y "development tools"
# Libraries needed during compilation to enable all features of Python:
yum install -y zlib-devel bzip2-devel openssl-devel ncurses-devel sqlite-devel readline-devel tk-devel gdbm-devel db4-devel libpcap-devel xz-devel expat-devel
# If you are on a clean "minimal" install of CentOS you also need the wget tool:
yum install -y wget

接下来的步骤取决于您安装的Python的版本。

对于Python 2.7.14：

wget http://python.org/ftp/python/2.7.14/Python-2.7.14.tar.xz
tar xf Python-2.7.14.tar.xz
cd Python-2.7.14
./configure --prefix=/usr/local --enable-unicode=ucs4 --enable-shared LDFLAGS="-Wl,-rpath /usr/local/lib"
make && make altinstall

# Strip the Python 2.7 binary:
strip /usr/local/lib/libpython2.7.so.1.0

wget http://python.org/ftp/python/3.6.3/Python-3.6.3.tar.xz
tar xf Python-3.6.3.tar.xz
cd Python-3.6.3
./configure --prefix=/usr/local --enable-shared LDFLAGS="-Wl,-rpath /usr/local/lib"
make && make altinstall

# Strip the Python 3.6 binary:
strip /usr/local/lib/libpython3.6m.so.1.0

安装PIP：

# First get the script:
wget https://bootstrap.pypa.io/get-pip.py

# Then execute it using Python 2.7 and/or Python 3.6:
python2.7 get-pip.py
python3.6 get-pip.py

# With pip installed you can now do things like this:
pip2.7 install [packagename]
pip2.7 install --upgrade [packagename]
pip2.7 uninstall [packagename]

您不应该更改Python的系统版本，因为它会破坏系统（正如您发现的那样）。安装其他版本很好，只要你离开原始的系统版本。这可以通过在运行configure时使用自定义前缀（例如/usr/local)，在安装Python构建时使用make altinstall（而不是普通的make install)来实现。

只要您记得键入包括版本号在内的全名（例如“Python2.7”或“PIP2.7”），多个可用的Python版本通常不是一个大问题。如果您从virtualenv中完成所有的Python工作，版本控制将为您处理，因此请确保安装并使用virtualenv！