I have Python on my Ubuntu system, but gcc can't find Python.h

Question

I am on a school computer, so I can't install anything.

I am trying to create C code which can be run in Python. It seems all the articles I am finding on it require you to use

#include <Python.h>

I do this, but when I compile it complains that there is no such file or directory.

The computer has Python (at least it has the python command in the terminal, and we can run whatever Python code we want).

I typed in locate Python.h in the terminal, but it found nothing.

I have two questions:

1. Can I write C code that I can call in Python without Python.h?

2. Am I missing something, and the computer actually has Python.h?

Solution 1

You need the python-dev package which contains Python.h

Solution 2

On Ubuntu, you would need to install a package called python-dev. Since this package doesn't seem to be installed (locate Python.h didn't find anything) and you can't install it system-wide yourself, we need a different solution.

You can install Python in your home directory -- you don't need any special permissions to do this. If you are allowed to use a web browser and run a gcc, this should work for you. To this end

1. Download the source tarball.

2. Unzip with

   tar xjf Python-2.7.2.tar.bz2
   

3. Build and install with

   cd Python-2.7.2
   ./configure --prefix=/home/username/python --enable-unicode=ucs4
   make
   make install
   

Now, you have a complete Python installation in your home directory. Pass -I /home/username/python/include to gcc when compiling to make it aware of Python.h. Pass -L /home/username/python/lib and -lpython2.7 when linking.

Solution 3

You have to use #include "python2.7/Python.h" instead of #include "Python.h".

Solution 4

For Ubuntu 15.10 and Python 3, comming to this question as they don't have Python.h but having administrative rights, the following might solve it:

sudo apt-get install python-dev
sudo apt-get install python3-dev
sudo apt-get install libpython3-dev
sudo apt-get install libpython3.4-dev
sudo apt-get install libpython3.5-dev

Solution 5

On ubuntu you can just type sudo apt-get install python-dev -y in terminal to install the python-dev package.

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Comments

[Andrew Marsh]

The questioner has stated that they are unable to install new packages on the system.

[user979344]

well, it mostly works. I am getting this error now: /home/pdem/python/Include/Python.h:8:22: error: pyconfig.h: No such file or directory....btw the computer is running python version 2.6.5...does that make a difference? thanks!

[Sven Marnach]

@user979344: I don't know the reason for the error message. The capital I in your path surprise me a bit -- you should use the Python.h from where you installed Python, not from where you unpacked the tarball. The Python version that was already installed does not matter -- you are installing your own Python, any version you want. It can coexist with the system-wide installation.

[Jesse Pepper]

I have installed python-dev in ubuntu 12.04 and get a /usr/include/python2.7 area but no python.h file exists in there. Any ideas?

[Jonathan Hartley]

python/Lib contains the Python modules of the stdlib. I think you mean -L...python/Python/, which contains some .c and .o files.

[Sven Marnach]

@JonathanHartley: No, I meant exactly what I wrote. You are confusing the path Lib/ in the source distribution with the path $prefix/lib of the installed software.

[Jonathan Hartley]

@SvenMarnach aha! I see. Thanks.

[RDK]

This solved it for me on a newly launched Ubuntu instance on AWS. sudo apt-get install libpython2.7-dev

[GreenMatt]

The OP says they're on a school computer, so sudo apt-get probably isn't available to them.

[Werner]

Some cases the package is called python-devel x)

[Jithin Pavithran]

Try locate Python.h and see if you already have the file before you do all this. If you can find the file located, mostly this answer will work: stackoverflow.com/a/19344978/4954434 (It might be just a path issue)

[m3nda]

Once you know where and how are the libs stored that makes more sense, nevermind to get a machine-produced file with no path specified :D

[fanny]

it works for ubuntu 16.04, too :) thank you, Martin!

[Shawn Anderson]

sudo apt-get install libpython3.6-dev solved it for me. Thanks!

[DLH]

You saved my life. I had python-dev installed and still couldn't get it to work until I saw your answer. Up-voting your answer so more people see this.

[nos]

For python3, it would be python3-config

[vineeshvs]

Command used: "$ gcc -Wall -I /home/vineesh/python/include insertion_sort.c -nostartfiles -L /home/vineesh/python/lib -lpython2.7 -o insertion_sort ". Getting the error: "/usr/include/numpy/ndarrayobject.h:17:20: fatal error: Python.h: No such file or directory compilation terminated."

[unlockme]

Bloody stuff, creating the symlink worked. I had tried everything else recommended without much success.

[Jekson]

sudo apt-get install libpython3.7-dev solved it for Ubuntu 18.04 and Python 3.7

[jrh]

If you are the owner of the C/C++ code including Python.h this may be a reasonable solution, if you're not, you may be better off editing a build script instead to change your include directories; I think the particular library I'm trying to use never imagined that Python 3 would ever be a thing. Another thing worth mentioning, I'd say under no circumstance should you do something like symlinking the Python2 headers or doing anything else to pretend both python versions are the same... on Linux systems this can be fatal because unfortunately Linux needs both Python 2 and 3 independently.

[johannes_lalala]

see danielcooperxyz's answer: gcc $(python-config --includes)

[N4ppeL]

What is the "correct" way to fix pip not finding Python.h ? I installed py3.7 on Ubuntu18, and libpython3.7-dev does not add any headers, but they exist in /usr/include/python3.6m. I could install the library with pip after creating a symlink python3.7m -> python3.6m, but as you stated, this is extremely problematic and should not be done. So what should be done instead?

[zappfinger]

I tried all of these, on Mint 20 python3.8.5 is installed, tried that too, to no avail...

[Klaas van Schelven]

python3-dev in current Ubuntu distributions (assuming Python 3)

[Mateen Ulhaq]

Or python3.7-dev, for Python 3.7.

[AntonK]

a hint for VisualStudio users - use back-quotes around python-config --includes if you want to add this helper into Additonal Options for C/C++