How can I find the installed python-lxml version in a Linux system?
>>> import lxml
>>> lxml.__version__
Traceback (most recent call last):
  F         
        You can use pip as well:
import pip
lxml_package = [pckg for pckg in pip.get_installed_distributions() 
                if pckg.project_name == 'lxml'][0] # assuming lxml is installed
print lxml_package.version
                                                                        from lxml import etree
etree.__version__
                                                                        I'm surprised that nobody suggested
pip show lxml
Here are two more ways to do it, with minimal typing. You could do it with pip from the command line:
$ pip freeze | grep lxml
lxml==3.2.5
Since you installed from ubuntu repository with apt-get you can also use dpkg:
$ dpkg -l python-lxml
Desired=Unknown/Install/Remove/Purge/Hold
| Status=Not/Inst/Cfg-files/Unpacked/Failed-cfg/Half-inst/trig-aWait/Trig-pend
|/ Err?=(none)/Reinst-required (Status,Err: uppercase=bad)
||/ Name                     Version                  Description
+++-========================-========================-================================================================
ii  python-lxml              2.2.4-1                  pythonic binding for the libxml2 and libxslt libraries
                                                                        You can get the version by looking at etree:
>>> from lxml import etree
>>> etree.LXML_VERSION
(3, 0, -198, 0)
Other versions of interest can be: etree.LIBXML_VERSION, etree.LIBXML_COMPILED_VERSION, etree.LIBXSLT_VERSION and etree.LIBXSLT_COMPILED_VERSION.
I assume you want to determine lxml's version programatically from Python. Since lxml does not provide this information via way of a typilca __version__ attribute on the top-level package you will have to resort to using setuptools' pkg_resources.require() function:
>>> from pkg_resources import require
>>> match = require("lxml")
>>> match
[lxml 3.3.0beta1 (/home/prologic/lib/python2.7/site-packages)]
>>> lxml = match[0]
>>> lxml.version
'3.3.0beta1'