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Python pip not working with egg_info error [duplicate]

I'm trying to install some packages with pip.
But pip install unroll gives me
Command "python setup.py egg_info" failed with error code 1 in
C:\Users\MARKAN~1\AppData\Local\Temp\pip-build-wa7uco0k\unroll\
How can I solve this?

About the error code
According to the Python documentation:
This module makes available standard errno system symbols. The value of each symbol is the corresponding integer value. The names and descriptions are borrowed from linux/include/errno.h, which should be pretty all-inclusive.
Error code 1 is defined in errno.h and means Operation not permitted.
About your error
Your setuptools do not appear to be installed. Just follow the Installation Instructions from the PyPI website.
If it's already installed, try
pip install --upgrade setuptools
If it's already up to date, check that the module ez_setup is not missing. If it is, then
pip install ez_setup
Then try again
pip install unroll
If it's still not working, maybe pip didn't install/upgrade setup_tools properly so you might want to try
easy_install -U setuptools
And again
pip install unroll

Here's a little guide explaining a little bit how I usually install new packages on Python + Windows. It seems you're using Windows paths, so this answer will stick to that particular SO:
I never use a system-wide Python installation. I only use virtualenvs, and usually I try to have the latest version of 2.x & 3.x.
My first attempt is always doing pip install package_i_want in some of my Visual Studio command prompts. What Visual Studio command prompt? Well, ideally the Visual Studio which matches the one which was used to build Python. For instance, let's say your Python installation says Python 2.7.11 (v2.7.11:6d1b6a68f775, Dec 5 2015, 20:40:30) [MSC v.1500 64 bit (AMD64)] on win32. The version of Visual Studio used to compile Python can be found here, so v1500 means I'd be using vs2008 x64 command prompt
If the previous step failed for some reason I just try using easy_install package_i_want
If the previous step failed for some reason I go to gohlke website and I check whether my package is available over there. If it's so, I'm lucky, I just download it into my virtualenv and then I just go to that location using a command prompt and I do pip install package_i_want.whl
If the previous step didn't succeed I'll just try to build the wheel myself and once it's generated I'll try to install it with pip install package_i_want.whl
Now, if we focus in your specific problem, where you're having a hard time installing the unroll package. It seems the fastest way to install it is doing something like this:
git clone https://github.com/Zulko/unroll
cd unroll && python setup.py bdist_wheel
Copy the generated unroll-0.1.0-py2-none-any.whl file from the created dist folder into your virtualenv.
pip install unroll-0.1.0-py2-none-any.whl
That way it will install without any problems. To check it really works, just login into the Python installation and try import unroll, it shouldn't complain.
One last note: This method works almost 99% of the time, and sometimes you'll find some pip packages which are specific to Unix or Mac OS X, in that case, when that happens I'm afraid the best way to get a Windows version is either posting some issues to the main developers or having some fun by yourself porting to Windows (typically a few hours if you're not lucky) :)

It was resolved after upgrading pip:
python -m pip install --upgrade pip
pip install "package-name"

I got stuck exactly with the same error with psycopg2. It looks like I skipped a few steps while installing Python and related packages.
sudo apt-get install python-dev libpq-dev
Go to your virtual env
pip install psycopg2
(In your case you need to replace psycopg2 with the package you have an issue with.)
It worked seamlessly.

I got this same error while installing mitmproxy using pip3. The below command fixed this:
pip3 install --upgrade setuptools

Download and install the Microsoft Visual C++ Compiler for Python 2.7 from https://www.microsoft.com/en-in/download/details.aspx?id=44266 - this package contains the compiler and set of system headers necessary for producing binary wheels for Python 2.7 packages.
Open a command prompt in elevated mode (run as administrator)
Firstly do pip install ez_setup
Then do pip install unroll (It will start installing numpy, music21, decorator, imageio, tqdm, moviepy, unroll) # Please be patient for music21 installation
Python 2.7.11 64 bit used

Other way:
sudo apt-get install python-psycopg2 python-mysqldb

I had the same issue when installing the "Twisted" library and solved it by running the following command on Ubuntu 16.04 (Xenial Xerus):
sudo apt-get install python-setuptools python-dev build-essential

It's a dependency issue.
I tried running the following commands helped me sorting out the dependencies, in my case the dependency was
grpcio
pip3 install --upgrade pip
python3 -m pip install --upgrade setuptools
pip3 install --no-cache-dir --force-reinstall -Iv grpcio==1.36.1
pip3 install pulsar-client==2.7.0
remember you must have python3 installed in your system.

First try:
pip install unroll
For sure not work :)
Then Try:
pip2 install unroll
Still get error Try:
pip3 install unroll
If pip3 Worked then suggest to change configuration to use pip3 as pip because you will get a lot of issues as the modern now is Python3 = pip3 if you execute a script files.

I had the same problem.
The problem was:
pyparsing 2.2 was already installed and my requirements.txt was trying to install pyparsing 2.0.1 which throw this error
Context: I was using virtualenv, and it seems the 2.2 came from my global OS Python site-packages, but even with --no-site-packages flag (now by default in last virtualenv) the 2.2 was still present. Surely because I installed Python from their website and it added Python libraries to my $PATH.
Maybe a pip install --ignore-installed would have worked.
Solution: as I needed to move forwards, I just removed the pyparsing==2.0.1 from my requirements.txt.

I ran into the same error code when trying to install a Python module with pip.
#Hackndo noted that the documentation indicate a security issue.
Based on that answer, my problem was solved by running the pip install command with sudo prefixed:
sudo pip install python-mpd2

For me this worked
python3 -m pip3 install -U pip
you can also try
python -m pip install -U pip

pip3 install --upgrade setuptools
WARNING: pip is being invoked by an old script wrapper. This will fail in a future version of pip.
Please see https://github.com/pypa/pip/issues/5599 for advice on fixing the underlying issue.
To avoid this problem you can invoke Python with -m pip instead of running pip directly.
Use python3 -m pip "command", eg:
python3 -m pip install --user pyqt5

I tried all of the above with no success. I then updated my Python version from 2.7.10 to 2.7.13, and it resolved the problems that I was experiencing.

That means some packages in pip are old or not correctly installed.
Try checking version and then upgrading pip.Use auto remove if that works.
If the pip command shows an error all the time for any command or it freezes, etc.
The best solution is to uninstall it or remove it completely.
Install a fresh pip and then update and upgrade your system.
I have given a solution to installing pip fresh here - python: can't open file get-pip.py error 2] no such file or directory

next installation helps me:
pip3 install cython

This worked for me:
sudo xcodebuild -license

Upgrading Python to version 3 fixed my problem. Nothing else did.

I downloaded the .whl file from http://www.lfd.uci.edu/~gohlke/pythonlibs/ and then did:
pip install scipy-0.19.1-cp27-cp27m-win32.whl
Note that the version you need to use (win32/win_amd-64) depends on the version of Python and not that of Windows.

I had this problem using virtualenvs (with pipenv) on my new development setup.
I could only solve it by upgrading the psycopg2 version from 2.6.2 to 2.7.3.
More information is at https://github.com/psycopg/psycopg2/issues/594

I faced the same problem with the same error message but on Ubuntu 16.04 LTS (Xenial Xerus) instead:
Command "python setup.py egg_info" failed with error code 1 in /tmp/pip-install-w71uo1rg/poster/
I tested all the solutions provided above and none of them worked for me. I read the full TraceBack and found out I had to create the virtual environment with Python version 2.7 instead (the default one uses Python 3.5 instead):
virtualenv --python=/usr/bin/python2.7 my_venv
Once I activated it, I run pip install unirest successfully.

try on linux:
sudo apt install python-pip python-bluez libbluetooth-dev libboost-python-dev libboost-thread-dev libglib2.0-dev bluez bluez-hcidump

Had the same problem on my Win10 PC with different packages and tried everything mentioned so far.
Finally solved it by disabling Comodo Auto-Containment.
Since nobody has mentioned it yet, I hope it helps someone.

I had the same problem and was able to fix by doing the following.
Windows Python needs Visual C++ libraries installed via the SDK to build code, such as via setuptools.extension.Extension or numpy.distutils.core.Extension. For example, building f2py modules in Windows with Python requires Visual C++ SDK as installed above. On Linux and Mac, the C++ libraries are installed with the compiler.
https://www.scivision.co/python-windows-visual-c++-14-required/

Following below command worked for me
[root#sandbox ~]# pip install google-api-python-client==1.6.4

Methods to solve setup.pu egg_info issue when updating setuptools or not other methods doesnot works.
If CONDA version of the library is available to install use conda instead of pip.
Clone the library repo and then try installation by pip install -e . or by python setup.py install

upgrading python's version did the work for me.

I have just encountered the same problem when trying to pip install -e . a new repo. I did not notice that the contents of setup.py haven't been saved properly and I was effectively running the command with an empty setup.py.
Hence you may experience the same error message if the setup.py of the target package is either empty or malformed.

I solved it on Centos 7 by using:
sudo yum install libcurl-devel

"Failed building wheel for psycopg2" - MacOSX using virtualenv and pip

I'm attempting to make a website with a few others for the first time, and have run into a weird error when trying to use Django/Python/VirtualEnv. I've found solutions to this problem for other operating systems, such as Ubuntu, but can't find any good solutions for Mac.
This is the relevant code being run:
virtualenv -p python3 venv
source venv/bin/activate
pip install -r requirements.txt
After running that block, I get the following errors:
AssertionError
Failed building wheel for django-toolbelt
Running setup.py bdist_wheel for psycopg2
...
AssertionError
Failed building wheel for psycopg2
Failed to build django-toolbelt psycopg2
I believe I've installed the "django-toolbelt" and "psycopg2", so I'm not sure why it would be failing.
The only difference I can think of is that I did not use the command
sudo apt-get install libpq-dev
as was instructed for Ubuntu usage as I believe that installing postgresql with brew took care of the header.
Thanks for any help or insight!

For MacOS users
After trying all the above methods (which did not work for me on MacOS 10.14), that one worked :
Install openssl with brew install openssl if you don't have it already.
add openssl path to LIBRARY_PATH :
export LIBRARY_PATH=$LIBRARY_PATH:/usr/local/opt/openssl/lib/
install psycopg2 with pip pip3 install psycopg2

I had the same problem on Arch linux. I think that it's not an OS dependant problem. Anyway, I fixed this by finding the outdated packages and updating then.
pip uninstall psycopg2
pip list --outdated
pip install --upgrade wheel
pip install --upgrade setuptools
pip install psycopg2

I was also getting same error.
Using Python 3.7.3 and pip 19.1.1.
I used following command.
pip install psycopg2-binary==2.8.3

TDLR
If you aren't used to installing Python C-extensions, and psycopg2 isn't a core part of your work, try
pip install psycopg2-binary
Building Locally
psycopg2 is a C-extension, so it requires compilation when being installed by pip. The Build Prerequisites section of the docs explain what must be done to make installation via pip possible. In summary (for psycopg 2.8.5):
a C compiler must be installed on the machine
the Python header files must be installed
the libpq header files must be installed
the pg_config program must be installed (it usually comes with the libpq headers) and on $PATH.
With these prerequisites satisfied, pip install psycopg2 ought to succeed.
Installing pre-compiled wheels
Alternatively, pip can install pre-compiled binaries so that compilation (and the associated setup) is not required. They can be installed like this:
pip install psycopg2-binary
The docs note that
The psycopg2-binary package is meant for beginners to start playing with Python and PostgreSQL without the need to meet the build requirements.
but I would suggest that psycopg2-binary is often good enough for local development work if you are not using psycopg2 directly, but just as a dependency.
Concluding advice
Read the informative installation documentation, not only to overcome installation issues but also to understand the impact of using the pre-compiled binaries in some scenarios.

I had same problem and this appears to be a Mojave Issue, I was able to resolve with:
sudo installer -pkg /Library/Developer/CommandLineTools/Packages/macOS_SDK_headers_for_macOS_10.14.pkg -target /

For Mac OS X users:
1. First check your postgresql path by running this command in terminal:
pg_config
If this fails lookup how to add pg_config to your path.
2. Next install Xcode Tools by running this command in terminal:
xcode-select --install
If you have both those sorted out now try to install psycopg2 again

For MacOS users, this question has the correct solution:
install command line tools if necessary:
xcode-select --install
then
env LDFLAGS="-I/usr/local/opt/openssl/include -L/usr/local/opt/openssl/lib" pip install psycopg2

I was also facing the same after running all the above commands, but the following two commands worked for me:
Instead of pip, use this:
sudo apt-get install libpq-dev
then run this command:
pip install psycopg2

On OS X, I was able to solve this by simply upgrading wheel before installing psycopg2:
pip install --upgrade wheel

For OSX Sierra users, it seems that an xcode update is the solution: Can't install psycopg2 package through pip install... Is this because of Sierra?

I tried all the above solutions but they did not work for me. What I did was change the psycopg2 version in my requirements.txt file from psycopg2==2.7.4 to psycopg2==2.7.6

Is your error message complete? the most encountered reason for failing to install psycopg2 on mac from pip is pg_config is not in path.
by the way, using macports or fink to install psycopg2 is more recommended way, so you don't have to worry about pg_config, libpq-dev and python-dev.
plus, are using Python 3.5? then upgrage your wheel to > 0.25.0 using pip.

I faced the same issue, but the answers above didn't work for me.
So this is what I did in my requirements.txt
psycopg2-binary==2.7.6.1 and it worked fine

I had this issue on several packages, including psycopg2, numpy, and pandas. I simply removed the version from the requirements.txt file, and it worked.
So instead of psycopg2-binary==2.7.6.1 I just had psycopg2-binary.

I know you are asking for development environment but if you are deploying on server say, Heroku. Just add below line in the requirements.txt of your project.
django-heroku==0.3.1
As this package itself will install the required packages like psycopg2 on server deployment.So let the server(heroku) should take care of it.

sudo apt install libpq-dev python3.X-dev
where X is the sub version,
these should be followed by :
pip install --upgrade wheel
pip install --upgrade setuptools
pip install psycopg2
Enjoy !!!

I solved my problem by updating/installing vs_BuildTools. The link to the software was given in the error itself.
Error Image

Fixed by installing python3.7-dev: sudo apt install python3.7-dev, based on the link.
Python: 3.7
Ubuntu: 20.04.3 LTS

Trying to install lxml for python, "Could not find function xmlCheckVersion in library libxml2." [duplicate]

I'm getting an error Could not find function xmlCheckVersion in library libxml2. Is libxml2 installed? when trying to install lxml through pip.
c:\users\f\appdata\local\temp\xmlXPathInitqjzysz.c(1) : fatal error C1083: Cannot open include file: 'libxml/xpath.h': No such file or directory
*********************************************************************************
Could not find function xmlCheckVersion in library libxml2. Is libxml2 installed?
*********************************************************************************
error: command 'C:\\Users\\f\\AppData\\Local\\Programs\\Common\\Microsoft\\Visual C++ for Python\\9.0\\VC\\Bin\\cl.exe' failed with exit status 2
I don't find any libxml2 dev packages to install via pip.
Using Python 2.7 and Python 3.x on x86 in a virtualenv under Windows 10.

Install lxml from http://www.lfd.uci.edu/~gohlke/pythonlibs/#lxml for your python version. It's a precompiled WHL with required modules/dependencies.
The site lists several packages, when e.g. using Win32 Python 3.11, use lxml‑4.9.0‑cp311‑cp311‑win32.whl.
Download the file, and then install with:
pip install C:\path\to\downloaded\file\lxml‑4.9.0‑cp311‑cp311‑win32.whl

I had this issue and realised that whilst I did have libxml2 installed, I didn't have the necessary development libraries required by the python package. Installing them solved the problem:
sudo apt-get install libxml2-dev libxslt1-dev
sudo pip install lxml

Try to use:
easy_install lxml
That works for me, win10, python 2.7.

On Mac OS X El Capitan I had to run these two commands to fix this error:
xcode-select --install
pip install lxml
Which ended up installing lxml-3.5.0
When you run the xcode-select command you may have to sign a EULA (so have an X-Term handy for the UI if you're doing this on a headless machine).

In case anyone else has the same issue as this on
Centos, try:
yum install python-lxml
Ubuntu
sudo apt-get install -y python-lxml
worked for me.

set STATICBUILD=true && pip install lxml
run this command instead, must have VS C++ compiler installed first
https://blogs.msdn.microsoft.com/pythonengineering/2016/04/11/unable-to-find-vcvarsall-bat/
It works for me with Python 3.5.2 and Windows 7

I tried install a lib that depends lxml and nothing works. I see a message when build was started: "Building without Cython", so after install cython with apt-get install cython, lxml was installed.

I had this issue and realized that while I did have libxml2 installed, I didn't have the necessary development libraries required by the python package.
1) Installing them solved the problem:
The site to download the file: Download
2) After Installing the file save it in a accessible folder
pip install *path to that file*

For some reason it doesn't work in python 3.11, but 3.10 works.
On windows, to install a module with a previous version, use
py -3.10 -m pip install lxml
if you want to install it in a venv, then use
py -3.10 -m venv .venv
.venv/Scripts/pip.exe install lxml
if you've set up the venv, then you can just use
pip install lxml
You also need to run the python program with that version. If you set up a venv, then you don't need to do this.
py -3.10 file.py

It is not strange for me that none of the solutions above came up, but I saw how the igd installation removed the new version and installed the old one, for the solution I downloaded this archive:https://pypi.org/project/igd/#files
and changed the recommended version of the new version: 'lxml==4.3.0' in setup.py
It works!

I got the same error for python 32 bit. After install 64bit, the problem was fixed.

I am using venv.
In my case it was enough to add lxml==4.6.3 to requirements.txt.
One library wanted earlier version and this was causing this error, so when I forced pip to use newest version (currently 4.6.3) installation was successful.

Cannot install Lxml on Mac OS X 10.9

I want to install Lxml so I can then install Scrapy.
When I updated my Mac today it wouldn't let me reinstall lxml, I get the following error:
In file included from src/lxml/lxml.etree.c:314:
/private/tmp/pip_build_root/lxml/src/lxml/includes/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
I have tried using brew to install libxml2 and libxslt, both installed fine but I still cannot install lxml.
Last time I was installing I needed to enable the developer tools on Xcode but since it's updated to Xcode 5 it doesn't give me that option anymore.
Does anyone know what I need to do?

You should install or upgrade the commandline tool for Xcode.
Try this in a terminal:
xcode-select --install

I solved this issue on Yosemite by both installing and linking libxml2 and libxslt through brew:
brew install libxml2
brew install libxslt
brew link libxml2 --force
brew link libxslt --force
If you have solved the problem using this method but it pops up again at a later time, you might need to run this before the four lines above:
brew unlink libxml2
brew unlink libxslt
If you are having permission errors with Homebrew, especially on El Capitan, this is a helpful document. In essence, regardless of OS X version, try running:
sudo chown -R $(whoami):admin /usr/local

You may solve your problem by running this on the commandline:
STATIC_DEPS=true pip install lxml
It sure helped me.
Explanations on docs

I tried most of the solutions above, but none of them worked for me. I'm running Yosemite 10.10, the only solution that worked for me was to type this in the terminal:
sudo CPATH=/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.9.sdk/usr/include/libxml2 CFLAGS=-Qunused-arguments CPPFLAGS=-Qunused-arguments pip install lxml
EDIT: If you are using virtualenv, the sudo in beginning is not needed.

This has been bothering me as well for a while. I don't know the internals enough about python distutils etc, but the include path here is wrong. I made the following ugly hack to hold me over until the python lxml people can do the proper fix.
sudo ln -s /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/libxml

Installing globally... OS X 10.9.2
xcode-select --install
sudo easy_install pip
sudo CPATH=/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.9.sdk/usr/include/libxml2 CFLAGS=-Qunused-arguments CPPFLAGS=-Qunused-arguments pip install lxml

instalation instructions on http://lxml.de/installation.html explain:
To speed up the build in test environments, e.g. on a continuous integration server, disable the C compiler optimisations by setting the CFLAGS environment variable:
CFLAGS="-O0" pip install lxml

None of the above worked for me on 10.9.2, as compilation bails out with following error:
clang: error: unknown argument: '-mno-fused-madd'
Which actually lead to cleanest solution (see more details in [1]):
export CFLAGS=-Qunused-arguments
export CPPFLAGS=-Qunused-arguments
pip install lxml
or following if installing globally
sudo pip install lxml
[1] clang error: unknown argument: '-mno-fused-madd' (python package installation failure)

xcode-select --install
sudo easy_install pip
sudo pip install lxml

I solved this issue on Yosemite by running the following commands:
xcode-select install #this may take several minutes.
pip install lxml

With homebrew, libxml2 is hidden to not interfere with the system libxml2, so pip must be helped a little in order to find it.
With bash:
LDFLAGS=-L`brew --prefix libxml2`/lib CPPFLAGS=-I`brew --prefix libxml2`/include/libxml2 pip install --user lxml
With fish:
env LDFLAGS=-L(brew --prefix libxml2)/lib CPPFLAGS=-I(brew --prefix libxml2)/include/libxml2 pip install --user lxml

I tried all the answers on this page, none of them worked for me. I'm running OS X Version 10.9.2
But this definitely works....like a charm:
ARCHFLAGS=-Wno-error=unused-command-line-argument-hard-error-in-future pip install lxml

OSX 10.9.2
sudo env ARCHFLAGS=-Wno-error=unused-command-line-argument-hard-error-in-future STATIC_DEPS=true pip install lxml

Unfortunately xcode-select --install did not work for me as I already had the latest version.
It's very strange but I solved the issue by opening XCode and accepting the Terms & Conditions. Re-running pip install lxml returned no errors after.

After successful install from pip (lxml 3.6.4) I was getting an error when importing the lxml.etree module.
I was searching endlessly to install this as a requisite for scrapy, and tried all the options, but finally this worked for me (mac osx 10.11 python 2.7):
$ STATIC_DEPS=true sudo easy_install-2.7 "lxml==2.3.5"
The older version of lxml seem to work with etree module.
Pip can often ignore the specified version of a package, for example when you have the newer version in the pip cache, thus the easy_install. The '-2.7' option is for python version, omit this if you are installing for python 3.x.

In my case, I must shutdown Kaspersky Antivirus before installing lxml by:
pip install lxml

before compiling add the path that to xmlversion.h into your environment.
$ set INCLUDE=$INCLUDE:/private/tmp/pip_build_root/lxml/src/lxml/
But make sure the path I've provided has the xmlversion.h file located inside. Then,
$ python setup.py install

pip did not work for me. I went to
https://pypi.python.org/pypi/lxml/2.3
and downloaded the macosx .egg file:
https://pypi.python.org/packages/2.7/l/lxml/lxml-2.3-py2.7-macosx-10.6-intel.egg#md5=52322e4698d68800c6b6aedb0dbe5f34
Then used command line easy_install to install the .egg file.

This post links to a solution that worked for me
Python3, lxml and "Symbol not found: _lzma_auto_decoder" on Mac OS X 10.9
hth

I met the same question and after days of working I resolved this problem on my OS X 10.9.4, with Python 3.4.1.
Here's my solution,
According to installing lxml from lxml.de,
A macport of lxml is available. Try something like port install py25-lxml
If you do not have MacPort, install it from MacPort.org. It's quite easy. You may also need a compiler, to install Xcode compiling tools, use xcode-select --install
Firstly I updated my port to the latest version via sudo port selfupdate,
Then I just type sudo port install libxml2 and several minutes later you should see libxml2 installed successfully. Probably you may also need libxslt to install lxml. To install libxslt, use:sudo port install libxslt.
Now, just type pip install lxml, it should work fine.

I am using OSX 10.9.2 and I get the same error.
Installation of the Xcode command line tools does not help for this particular version of OSX.
I think a better approach to fix this is to install with the following command:
$ CPATH=/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.9.sdk/usr/include/libxml2 pip install lxml
This is similar to jdkoftinoff' fix, but does not alter your system in a permanent way.

After much tearing of the hair and gnashing of the teeth, I uninstalled Xcode with pip and ran:
easy_install lxml
And all was well.

Try:
% STATIC_DEPS=true pip install lxml
Or:
% STATIC_DEPS=true sudo pip install lxml
It works!

How do you install lxml on OS X Leopard without using MacPorts or Fink?

I've tried this and run in to problems a bunch of times in the past. Does anyone have a recipe for installing lxml on OS X without MacPorts or Fink that definitely works?
Preferably with complete 1-2-3 steps for downloading and building each of the dependencies.

Thanks to #jessenoller on Twitter I have an answer that fits my needs - you can compile lxml with static dependencies, hence avoiding messing with the libxml2 that ships with OS X. Here's what worked for me:
cd /tmp
curl -O http://lxml.de/files/lxml-3.6.0.tgz
tar -xzvf lxml-3.6.0.tgz
cd lxml-3.6.0
python setup.py build --static-deps --libxml2-version=2.7.3 --libxslt-version=1.1.24
sudo python setup.py install

This worked for me (10.6.8):
sudo env ARCHFLAGS="-arch i386 -arch x86_64" easy_install lxml

I've had excellent luck with Homebrew to install the libxml2 dependency:
brew install libxml2
Homebrew doesn't seem to have libxslt available, but I've not yet had a need for XSLT. YMMV.
Once you have the dependency(s), then the usual methods work just fine:
pip install lxml
or
easy_install lxml

Easy_install can work using this:
STATIC_DEPS=true easy_install 'lxml>=2.2beta4'
you may then need to run, depending on permissions;
STATIC_DEPS=true sudo easy_install 'lxml>=2.2beta4'
see
http://muffinresearch.co.uk/archives/2009/03/05/install-lxml-on-osx/

using homebrew (0.9.5) on el capitan (10.11.1) the following worked for me:
brew install libxml2
LD_FLAGS=-L/usr/local/opt/libxml2/lib CPPFLAGS=-I/usr/local/opt/libxml2/include/libxml2 pip install lxml

This worked for me on 10.8.5
Install Xcode from Mac App Store
Xcode -> Preferences -> Downloads -> Command Line Tools
Install homebrew using
ruby -e "$(curl -fsSL https://raw.github.com/mxcl/homebrew/go)"
brew install libxml2
sudo easy_install lxml
This comprises suggestions from:
https://stackoverflow.com/a/6545556/300224
https://stackoverflow.com/a/5785013/300224
https://stackoverflow.com/a/9403589
But I wanted to compile it into one answer rather than leave comments everywhere

On OS X 10.9.1 the suggested answer above errors out during install -- following changes had to be made:
cd /tmp
curl -o lxml-3.3.0.tgz http://lxml.de/files/lxml-3.3.0.tgz
tar -xzvf lxml-3.3.0.tgz
cd lxml-3.3.0
python setup.py build --static-deps --libxml2-version=2.8.0 --libxslt-version=1.1.24
sudo python setup.py install

I had this working fine with Snow Lepoard but after I upgraded to Lion I had to symlink gcc-4.2 to gcc. Running sudo env ARCHFLAGS="-arch i386 -arch x86_64" easy_install lxml was looking for gcc-4.2 instead of gcc.

I'm using OSX 10.11 El Capitan and Homebrew. Using pip install lxml would give me "fatal error: 'libxml/xmlversion.h' file not found" and "failed with error code 1" blah blah.
According to the official website, I should use STATIC_DEPS=true pip install lxml (add sudo before pip if you need that), and that solved my problem.
I ran brew install libxml2 and brew install libxslt to install the dependencies while troubleshooting. I'm not sure if those two commands are necessary.

Try installing Cython and installing from source, easy_install does fail. I haven't tried on my mac yet though.
Failing that the ports version isn't that ancient. You can see the dependencies, some of which had to be updated for my Linux build of lxml.
info py25-lxml
py25-lxml #2.1.5 (python, devel)
lxml is a Pythonic binding for the libxml2 and libxslt libraries. It is unique
in that it combines the speed and feature completeness of these libraries with
the simplicity of a native Python API, mostly compatible but superior to the
well-known ElementTree API.
Homepage: http://codespeak.net/lxml/
Library Dependencies: python25, libxml2, libxslt, py25-hashlib, py25-setuptools,
py25-zlib
Platforms: darwin
Maintainers: akitada#macports.org openmaintainer#macports.org

This is quite up to date - march 2009: http://lsimons.wordpress.com/2008/08/31/how-to-install-lxml-python-module-on-mac-os-105-leopard/

lxml is included in the pypm repository:
$ pypm install lxml

To install with up to date versions of libxml2 and libxslt:
ARCHFLAGS="-arch i386 -arch x86_64" STATIC_DEPS=true pip install lxml
To install with specific versions of libraries:
ARCHFLAGS="-arch i386 -arch x86_64" STATIC_DEPS=true LIBXML2_VERSION=2.7.3 LIBXSLT_VERSION=1.1.24 pip install lxml
CentOS 64 bit (a bit off question, but hard won):
CFLAGS=-fPIC STATIC_DEPS=true pip install lxml
or
CFLAGS=-fPIC STATIC_DEPS=true LIBXML2_VERSION=2.7.3 LIBXSLT_VERSION=1.1.24 pip install lxml

A lot of pain went into this for an outdated 10.6.8 os x but here it goes for anyone running Snow Leopard!
First you have to install a different version of libxml2 from homebrew and install --with-python. You can do this by typing in the following commands.
brew update
brew edit libxml2
Then find the line that says "--without-python" and change to "--with-python".
system "./configure", "--disable-dependency-tracking",
"--prefix=#{prefix}",
"--with-python"
Now you can install libxml2.
brew install libxml2
Next check your new install of libxml2 in the default homebrew location. You want to find the libxml2 config.
YOURS MAY BE DIFFERENT:
"/usr/local/Cellar/libxml2/VERSION_/bin/xml2-config"
Now use the following command to install lxml with pip using the newly installed libxml2 config and not the Mac OS X version.
ARCHFLAGS="-arch i386 -arch x86_64" pip install lxml --install-option="--with-xml2-config=/usr/local/Cellar/libxml2/2.9.1/bin/xml2-config"
Worked for me on my 10.6.8 Python 2.6. Thanks.
Credit goes to this page for showing me pip --install-option ...
http://natanyellin.com/page/4/

I compile it in /usr/local without any issues whatsoever.
Install Python, libxml2, libxslt and then lxml. You might need setuptools installed too.