Centos7下成功安裝python3和scrapy爬虫

1、安装python3（保留python2）

（1）源码编译前准备

yum -y groupinstall "Development tools"

yum -y install zlib-devel bzip2-devel openssl-devel ncurses-devel sqlite-devel readline-devel tk-devel gdbm-devel db4-devel libpcap-devel xz-devel

如果上面命名报错，按照提示加上--skip-broken

yum -y install zlib-devel bzip2-devel openssl-devel ncurses-devel sqlite-devel readline-devel tk-devel gdbm-devel db4-devel libpcap-devel xz-devel --skip-broken

（2）下载Python-3.5源码

wget https://www.python.org/ftp/python/3.5.5/Python-3.5.5.tgz

然后解压缩，进入根目录

tar -zxvf Python-3.5.5.tgz 
cd Python-3.5.5/

（3）编译安装

./configure --prefix=/usr/local/python3
make && make install

（4）创建软链接

ln -s /usr/local/python3/bin/python3 /usr/bin/python3
ln -s /usr/local/python3/bin/pip3 /usr/bin/pip3
如果file exists 用f参数
ln -sf /usr/local/python3/bin/pip3 /usr/bin/pip3

（5）验证

[root@hadron ~]# python
Python 2.7.5 (default, Nov  6 2016, 00:28:07) 
[GCC 4.8.5 20150623 (Red Hat 4.8.5-11)] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> quit()
[root@hadron ~]# python3
Python 3.5.5 (default, Feb 27 2018, 09:28:49) 
[GCC 4.8.5 20150623 (Red Hat 4.8.5-11)] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> quit()
[root@hadron ~]# 

2、安装scrapy爬虫

（1）安装scrapy

[root@hadron ~]# pip3 install scrapy
Collecting scrapy
  Downloading Scrapy-1.5.0-py2.py3-none-any.whl (251kB)
    100% |████████████████████████████████| 256kB 1.1MB/s 
Requirement already satisfied: lxml in /usr/local/python3/lib/python3.5/site-packages (from scrapy)
Collecting PyDispatcher>=2.0.5 (from scrapy)
  Downloading PyDispatcher-2.0.5.tar.gz
....
....
Collecting pycparser (from cffi>=1.7; platform_python_implementation != "PyPy"->cryptography>=2.1.4->pyOpenSSL->scrapy)
  Downloading pycparser-2.18.tar.gz (245kB)
    100% |████████████████████████████████| 256kB 339kB/s 
Installing collected packages: PyDispatcher, zope.interface, constantly, incremental, six, attrs, Automat, hyperlink, Twisted, cssselect, w3lib, parsel, asn1crypto, pycparser, cffi, cryptography, pyOpenSSL, pyasn1, pyasn1-modules, service-identity, queuelib, scrapy
  Running setup.py install for PyDispatcher ... done
  Running setup.py install for Twisted ... done
  Running setup.py install for pycparser ... done
Successfully installed Automat-0.6.0 PyDispatcher-2.0.5 Twisted-17.9.0 asn1crypto-0.24.0 attrs-17.4.0 cffi-1.11.4 constantly-15.1.0 cryptography-2.1.4 cssselect-1.0.3 hyperlink-18.0.0 incremental-17.5.0 parsel-1.4.0 pyOpenSSL-17.5.0 pyasn1-0.4.2 pyasn1-modules-0.2.1 pycparser-2.18 queuelib-1.4.2 scrapy-1.5.0 service-identity-17.0.0 six-1.11.0 w3lib-1.19.0 zope.interface-4.4.3
[root@hadron ~]#

（2）在python3 shell中验证scrapy

[root@hadron ~]# python3
Python 3.5.5 (default, Feb 27 2018, 09:28:49) 
[GCC 4.8.5 20150623 (Red Hat 4.8.5-11)] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import scrapy
>>> scrapy.version_info
(1, 5, 0)
>>>

（3）创建软scrapy链接

[root@hadron ~]# ln -s /usr/local/python3/bin/scrapy  /usr/bin/scrapy

（4）在shell中验证scrapy

[root@hadron ~]# scrapy
Scrapy 1.5.0 - no active project

Usage:
  scrapy <command> [options] [args]

Available commands:
  bench         Run quick benchmark test
  fetch         Fetch a URL using the Scrapy downloader
  genspider     Generate new spider using pre-defined templates
  runspider     Run a self-contained spider (without creating a project)
  settings      Get settings values
  shell         Interactive scraping console
  startproject  Create new project
  version       Print Scrapy version
  view          Open URL in browser, as seen by Scrapy

  [ more ]      More commands available when run from project directory

Use "scrapy <command> -h" to see more info about a command
[root@hadron ~]# 

[root@hadron ~]# scrapy -v
Scrapy 1.5.0 - no active project

Usage:
  scrapy <command> [options] [args]

Available commands:
  bench         Run quick benchmark test
  fetch         Fetch a URL using the Scrapy downloader
  genspider     Generate new spider using pre-defined templates
  runspider     Run a self-contained spider (without creating a project)
  settings      Get settings values
  shell         Interactive scraping console
  startproject  Create new project
  version       Print Scrapy version
  view          Open URL in browser, as seen by Scrapy

  [ more ]      More commands available when run from project directory

Use "scrapy <command> -h" to see more info about a command
[root@hadron ~]#

按照同理可以安装python3.9.2 一样可以安装scrapy成功
升级pip
/usr/local/python3/bin/python3.9 -m pip install --upgrade pip
降级
python -m pip install pip==版本（如：9.0.3）