python learning notes: Alibaba (Tencent) cloud upgrade python

python introduction

Supported systems: cross platform
 Advantages: high development efficiency
 Disadvantages: slow execution
 Application: website development, automatic operation and maintenance, game development, crawler, data analysis, artificial intelligence

Alibaba cloud and Tencent cloud

View python version

[root@Tencent ~]# python
Python 2.7.5 (default, Aug  7 2019, 00:51:29) 
[GCC 4.8.5 20150623 (Red Hat 4.8.5-39)] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> 

The default Python version of Alibaba cloud and Tencent cloud systems is 2.7. Since Python officially announced that Python 2 will be disabled in 2020, python will be upgraded directly

1,download python Installation package
[root@Tencent ~]#wget https://www.python.org/ftp/python/3.5.0/Python-3.5.0.tar.xz

2,decompression
[root@Tencent ~]# tar -xf Python-3.5.0.tar.xz 

3,Compilation and installation
[root@Tencent ~]# cd Python-3.5.0/
[root@Tencent Python-3.5.0]# ./configure --prefix=/usr/local/python3
[root@Tencent Python-3.5.0]# make && make install

4,backups python2.7
[root@Tencent Python-3.5.0]# mv /usr/bin/python /usr/bin/python2.7.bak

5,to python3 Create a soft connection
[root@Tencent Python-3.5.0]# ln -sv /usr/local/python3/bin/python3.5 /usr/bin/python
?.usr/bin/python?.-> ?.usr/local/python3/bin/python3.5?

6,See python Version and backspace key and direction key use
[root@Tencent Python-3.5.0]# python
Python 3.5.0 (default, Feb 11 2020, 13:26:01) 
[GCC 4.8.5 20150623 (Red Hat 4.8.5-39)] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> 

If you find that python3 backspace and direction key cannot be used normally, please install the readline library file. Since the cloud server is used, you can configure the yum source policy for reference https://blog.51cto.com/14015577/2414577

7,install readline Library file
[root@VM_0_4_centos ~]# yum install readline-devel.* -y

It is found that yum cannot be used at this time. It is necessary to modify the path of python of / usr/bin/yum and / usr / libeec / urlgrabber ext-down to the system's own version, such as / usr/bin/python2.7

8,modify yum Interpreter
[root@Tencent ~]# head -n 1 /usr/bin/yum
#!/usr/bin/python2.7
[root@Tencent ~]]# head -n 1 /usr/libexec/urlgrabber-ext-down 
#! /usr/bin/python2.7

//Install readline library file
[root@Tencent ~]yum install readline-devel.* -y

9,install readline Library succeeded, reinstall compilation python
[root@Tencent Python-3.5.0]# ./configure --prefix=/usr/local/python3
[root@Tencent Python-3.5.0]# make && make install

10,to python3 Create a soft connection
[root@Tencent Python-3.5.0]# ln -sv /usr/local/python3/bin/python3.5 /usr/bin/python
?.usr/bin/python?.-> ?.usr/local/python3/bin/python3.5?

python backspace and direction key can be used normally

11,See python Version and backspace key and direction key use
[root@Tencent Python-3.5.0]# python
Python 3.5.0 (default, Feb 11 2020, 13:26:01) 
[GCC 4.8.5 20150623 (Red Hat 4.8.5-39)] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> 

Because Yum uses Python as the interpreter, and adds alias to python3, so it doesn't need to change the interpreter of yum, directly in the
After the completion of 3-step compilation and installation, the operation will be completed. At this time, python3 can use aliases, and backspace key and direction key can be used normally. This method omits all steps after step 3.

Temporary change    
[root@Tencent Python-3.5.0]# alias python3=/usr/local/python3/bin/python3.5
//Permanent change
[root@Tencent Python-3.5.0]#vim ~/.bashrc 
alias python3=/usr/local/python3/bin/python3.5

[root@Tencent Python-3.5.0]# python
Python 2.7.5 (default, Aug  7 2019, 00:51:29) 
[GCC 4.8.5 20150623 (Red Hat 4.8.5-39)] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> 

[root@VM_0_4_centos ~]# python3
Python 3.5.0 (default, Feb 11 2020, 14:11:53) 
[GCC 4.8.5 20150623 (Red Hat 4.8.5-39)] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> print('hello world!')
hello world!

Tags: Linux Python yum Red Hat

Posted on Wed, 12 Feb 2020 10:12:00 -0500 by DapperDanMan