最近在看一个自动化测试框架的问题，需要用到Lxml库，下载lxml总是报错。
1，使用pip安装lxml
pip install lxml
2，然后报错了，报错内容是：
In file included from src/lxml/lxml.etree.c:139:src/lxml/etree_defs.h:9:10: fatal error: 'libxml/xmlversion.h' file not found#include "libxml/xmlversion.h" ^1 error generated.error: command 'cc' failed with exit status 1----------------------------------------Cleaning up...Command /usr/bin/python -c "import setuptools, tokenize;__file__='/private/var/folders/rc/0lpvj1710n332qg8p2wgcqyr0000gn/T/pip_build_cindy_mac/lxml/setup.py';exec(compile(getattr(tokenize, 'open', open)(__file__).read().replace('/r/n', '/n'), __file__, 'exec'))" install --record /var/folders/rc/0lpvj1710n332qg8p2wgcqyr0000gn/T/pip-xwdVzY-record/install-record.txt --single-version-externally-managed --compile failed with error code 1 in /private/var/folders/rc/0lpvj1710n332qg8p2wgcqyr0000gn/T/pip_build_cindy_mac/lxmlStoring debug log for failure in /Users/cindy_mac/Library/Logs/pip.log
3，然后百度了N久N久，借鉴了一个大神的方案，http://blog.marchtea.com/archives/91
4，找到进入Application->XCode，右键选择：显示内容，按照下面代码的路径一步一步往下跟：复制路径：/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.9.sdk/usr/include
然后在终端输入：
C_INCLUDE_PATH=/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.9.sdk/usr/include/libxml2:/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.9.sdk/usr/include/libxml2/libxml:/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.9.sdk/usr/include
5，然后再次使用pip安装
pip install lxml
6，看到成功了！！！
Downloading/unpacking lxmlDownloading lxml-3.4.1.tar.gz (3.5MB): 3.5MB downloadedRunning setup.py (path:/private/var/folders/rc/0lpvj1710n332qg8p2wgcqyr0000gn/T/pip_build_cindy_mac/lxml/setup.py) egg_info for package lxml/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/distutils/dist.py:267: UserWarning: Unknown distribution option: 'bugtrack_url'warnings.warn(msg)Building lxml version 3.4.1.Building without Cython.Using build configuration of libxslt 1.1.28warning: no previously-included files found matching '*.py'Installing collected packages: lxmlRunning setup.py install for lxml/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/distutils/dist.py:267: UserWarning: Unknown distribution option: 'bugtrack_url'warnings.warn(msg)Building lxml version 3.4.1.Building without Cython.Using build configuration of libxslt 1.1.28building 'lxml.etree' extensioncc -fno-strict-aliasing -fno-common -dynamic -arch x86_64 -arch i386 -g -Os -pipe -fno-common -fno-strict-aliasing -fwrapv -DENABLE_DTRACE -DMACOSX -DNDEBUG -Wall -Wstrict-prototypes -Wshorten-64-to-32 -DNDEBUG -g -fwrapv -Os -Wall -Wstrict-prototypes -DENABLE_DTRACE -arch x86_64 -arch i386 -pipe -I/usr/include/libxml2 -I/private/var/folders/rc/0lpvj1710n332qg8p2wgcqyr0000gn/T/pip_build_cindy_mac/lxml/src/lxml/includes -I/System/Library/Frameworks/Python.framework/Versions/2.7/include/python2.7 -c src/lxml/lxml.etree.c -o build/temp.macosx-10.9-intel-2.7/src/lxml/lxml.etree.o -w -flat_namespacecc -bundle -undefined dynamic_lookup -arch x86_64 -arch i386 -Wl,-F. build/temp.macosx-10.9-intel-2.7/src/lxml/lxml.etree.o -lxslt -lexslt -lxml2 -lz -lm -o build/lib.macosx-10.9-intel-2.7/lxml/etree.sobuilding 'lxml.objectify' extensioncc -fno-strict-aliasing -fno-common -dynamic -arch x86_64 -arch i386 -g -Os -pipe -fno-common -fno-strict-aliasing -fwrapv -DENABLE_DTRACE -DMACOSX -DNDEBUG -Wall -Wstrict-prototypes -Wshorten-64-to-32 -DNDEBUG -g -fwrapv -Os -Wall -Wstrict-prototypes -DENABLE_DTRACE -arch x86_64 -arch i386 -pipe -I/usr/include/libxml2 -I/private/var/folders/rc/0lpvj1710n332qg8p2wgcqyr0000gn/T/pip_build_cindy_mac/lxml/src/lxml/includes -I/System/Library/Frameworks/Python.framework/Versions/2.7/include/python2.7 -c src/lxml/lxml.objectify.c -o build/temp.macosx-10.9-intel-2.7/src/lxml/lxml.objectify.o -w -flat_namespacecc -bundle -undefined dynamic_lookup -arch x86_64 -arch i386 -Wl,-F. build/temp.macosx-10.9-intel-2.7/src/lxml/lxml.objectify.o -lxslt -lexslt -lxml2 -lz -lm -o build/lib.macosx-10.9-intel-2.7/lxml/objectify.soSuccessfully installed lxmlCleaning up...
7，为了保险，然后测试一下：
Cindy-macdeMacBook-Pro:Users cindy_mac$ pythonPython 2.7.5 (default, Mar9 2014, 22:15:05) [GCC 4.2.1 Compatible Apple LLVM 5.0 (clang-500.0.68)] on darwinType "help", "copyright", "credits" or "license" for more information.>>> import lxml>>> exit()