一.了解
CentOS中如果安装有yum,一般会有python2的某个版本。命令行键入python,出现的python2的环境:
[root@instance-hrnebyqu src]# python Python 2.7.5 (default, Apr 11 2018, 07:36:10) [GCC 4.8.5 20150623 (Red Hat 4.8.5-28)] on linux2 Type "help", "copyright", "credits" or "license" for more information.
我们希望将python这个shell指令连接到python3的版本。这里首先装python3,然后将python连接到python3上。
由于路径添加到了bash_profile文件中的PATH中了,因此环境变量不需要再改了。如果没有天津爱到哦环境变量则需要
vim ~/.bash_profile
把Python3的路径加上,然后重载bash_profile这个文件
接着修改bashrc这个文件
vim ~/.bashrc
将python2和python3 的路径都写上,并将python指定为python3
alias python2=/usr/bin/python alias python3=/usr/local/python3/bin/python3 alias python=/usr/local/python3/bin/python3
这样,命令行开python就是python3了。
[root@instance-hrnebyqu src]# python Python 3.6.6 (default, Jul 4 2019, 12:00:29) [GCC 4.8.5 20150623 (Red Hat 4.8.5-36)] on linux Type "help", "copyright", "credits" or "license" for more information.
注意:
在centos中,用于软件安装的yum指令是调用python昨晚命令解释器的,因此其默认版本为Python2,如果改成python3,会由于2和3的兼容性问题导致yum可能出现故障。因此需要特别注意。
yum 的路径在
/usr/bin/yum
可以看一下yum文件
#!/usr/bin/python import sys try: import yum except ImportError: print >> sys.stderr, """\ There was a problem importing one of the Python modules required to run yum. The error leading to this problem was: %s 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: %s If you cannot solve this problem yourself, please go to the yum faq at: http://yum.baseurl.org/wiki/Faq """ % (sys.exc_value, sys.version) sys.exit(1) sys.path.insert(0, \'/usr/share/yum-cli\') try: import yummain yummain.user_main(sys.argv[1:], exit_code=True) except KeyboardInterrupt, e:
可以看到,开头默认了解释器为/usr/bin/python。如果yum因为修改了python解释器出现bug,可以将这个改成/usr/bin/python2.x即可。