我将centos6.7上的python更新为python2.7.3，并将新版本作为默认版本。然后我使用sudo yum install python-lxml来安装python-lxml。显示
package python-lxml-2.2.3-1.1.el6.x86_64 has been installed and is the newest,there is nothing to do
但当我使用python（默认2.7.3）python和import lxml时，错误如下ImportError:没有名为lxml的模块。然而，当我使用像/usr/bin/python2.6和import lxml这样的旧版本python时，不会发生任何错误。lxml适用于旧版本的python。
怎么了？
我尝试了许多其他方法：
1.使用pip安装lxml sudo /usr/local/bin/pip install lxml，但发生错误
src/lxml/lxml.etree.c:237975: error：expected ‘)’ before ‘value’
Compile failed: command 'gcc' failed with exit status 1
cc -I/usr/include/libxml2 -I/usr/include/libxml2 -c
/tmp/xmlXPathInitB69jpu.c -o tmp/xmlXPathInitB69jpu.o
/tmp/xmlXPathInitB69jpu.c:1:26: error：libxml/xpath.h：no such file or directory
Could not find function xmlCheckVersion in library libxml2. Is libxml2 installed?
error: command 'gcc' failed with exit status 1
Command /usr/bin/python -c "importsetuptools;__file__='/home/zhoulipeng/software/lxml-3.4.4/build/lxml/setup.py';exec(compile(open(__file__).read().replace('rn', 'n'), __file__, 'exec'))" install --single-version-externally-managed --record /tmp/pip-VIpDJ1-record/install-record.txt failed with error code 1 4
似乎没有安装libxml2，所以我安装了所有的依赖项sudo yum install libxml2-devel libxslt-devel python-devel，它显示：
package libxml2-devel-2.7.6-20.el6.x86_64 has been installed and is the newest
package libxslt-devel-1.1.26-2.el6_3.1.x86_64 has been installed and is the newest
package python-devel-2.6.6-64.el6.x86_64 has been installed and is the newest
这意味着我已经安装了程序包libxml2。
2.从源代码安装lxml
当我用sudo python setup.py build构建源代码时，它失败了src/lxml/lxml.etree.c:201156:error:expected ')'before'__pyx_f_4lxml_5etree_xslt_doc_loader'error: command 'gcc' failed with exit status 1
有人能帮我吗？非常感谢。
百胜在pythons 2.6路径中安装了lxml。您需要为python 2.7搜索rpm或构建自己的rpm。
如果提供python 27的人也为lxml构建了rpm。
如果你通过redhat的软件集合安装了python27，你也可以尝试：
yum install python27-python-pip -y
scl enable python27 bash
pip install lxml
# python
Python 2.7.8 (default, Jun 9 2015, 19:27:51)
[GCC 4.4.7 20120313 (Red Hat 4.4.7-11)] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> import lxml
>>>