环境如下：
- Centos6.4
- Python 2.7.6
pip install lxml
执行上面的命令，有类似下面的提示：
src/lxml/lxml.etree.c:188133: error: ‘xsltDocDefaultLoader’ undeclared (first use in this function)
src/lxml/lxml.etree.c:188142: warning: implicit declaration of function ‘xsltSetLoaderFunc’
src/lxml/lxml.etree.c:188142: error: ‘xsltDocLoaderFunc’ undeclared (first use in this function)
src/lxml/lxml.etree.c:188142: error: expected ‘)’ before ‘__pyx_f_4lxml_5etree__xslt_doc_loader’
src/lxml/lxml.etree.c:188393: warning: implicit declaration of function ‘xsltRegisterAllExtras’
src/lxml/lxml.etree.c:188402: warning: implicit declaration of function ‘exsltRegisterAll’
error: Setup script exited with error: command 'gcc' failed with exit status 1
像这种情况，一般是对应的devel包没有安装，但是即使我安装了libxml2 和libxml2-devel，还是同样的提示
已经确认过gcc, gcc-c++等基础包安装的了
[root@localhost]$ rpm -qa |grep gcc
gcc-4.4.7-4.el6.x86_64
libgcc-4.4.7-4.el6.x86_64
gcc-c++-4.4.7-4.el6.x86_64
查看pypi上lxml的文档 lxml 3.4.1,可以在第一段就看到下面的一句话：
Powerful and Pythonic XML processing library combining libxml2/libxslt with the ElementTree API.
这里指出了lxml 会使用到 libxml2/libxsl
yum search libxml
yum search libxsl
会发现有libxslt-devel和libxml2-devel
执行shell命令：
yum -y install libxslt-devel
上面的命令执行之后，会自动安装和更新如下的软件包:
- libxml2
- libxml2-devel
- libgpg-error-devel
- libgcrypt-devel
- libxslt
- libxslt-devel
安装上面了6个软件包之后，pip install lxml就能成功安装lxml了