# Calling Python from C - error loading shared libraries

**URL:** <https://forum.anaconda.com/t/calling-python-from-c-error-loading-shared-libraries/25861>\
**Category:** Technical Topics\
**Created:** [June 22, 2022, 9:22pm UTC](https://forum.anaconda.com/t/calling-python-from-c-error-loading-shared-libraries/25861 "2022-06-22T21:22:58Z")\
**Posts on this page:** 4\
**Page:** 1

<div class="post-metadata">

**Author:** ![jjameson](https://avatars.discourse-cdn.com/v4/letter/j/80bc00/32.png) [@jjameson](https://forum.anaconda.com/u/jjameson)\
**Post date:** [June 22, 2022, 9:22pm UTC](https://forum.anaconda.com/t/calling-python-from-c-error-loading-shared-libraries/25861/1 "2022-06-22T21:22:58Z")

</div>

Disclaimer: this post is very similar to [a question I asked on StackOverflow](https://stackoverflow.com/questions/72609361/error-while-loading-shared-libraries-libpython3-9-so-1-0-anaconda-python3-9-c-e) a week ago.

I’m using Anaconda as a package manager for a project. I’m trying to call a Python function from C, but when I try to run the compiled program, I get the following error:

```bash
~/Documents/code/test: error while loading shared libraries: libpython3.9.so.1.0: cannot open shared object file: No such file or directory
[1] + Done "/usr/bin/gdb" --interpreter=mi --tty=${DbgTerm} 0<"/tmp/Microsoft-MIEngine-In-cdpcz1c5.vwd" 1>"/tmp/Microsoft-MIEngine-Out-j5b1thxt.2vz"

```

I’m including the library `${HOME}/anaconda3/envs/myenv/lib` and there is a `libpython3.9.so.1.0` file within this directory. When I use the command: `find ~/anaconda3/envs/myenv/ -name libpython3.9.so.*` , I get this result:

```bash
~/anaconda3/envs/myenv/lib/libpython3.9.so.1.0

```

The build command I’m using is:

```bash
/usr/bin/gcc -I${HOME}/Documents/git/resist/code \ 
    -I/usr/include/glib-2.0 \
    -I/usr/lib/x86_64-linux-gnu/glib-2.0/include \
    -I${HOME}/anaconda3/envs/myenv/include/python3.9 \
    -I${HOME}/anaconda3/envs/myenv/lib/python3.9/site-packages/numpy/core/include/numpy \
    -Wno-unused-result \
    -Wsign-compare \
    -march=nocona \
    -mtune=haswell \
    -ftree-vectorize \
    -fPIC \
    -fstack-protector-strong \
    -fno-plt \
    -O3 \
    -ffunction-sections \
    -pipe \
    -isystem ${HOME}/anaconda3/envs/myenv/include \
    -fdebug-prefix-map=/opt/conda/conda-bld/python-split_1649141344976/work=/usr/local/src/conda/python-3.9.12 \
    -fdebug-prefix-map=${HOME}/anaconda3/envs/myenv=/usr/local/src/conda-prefix \
    -I${HOME}/anaconda3/envs/myenv/include \
    -DNDEBUG \
    -O3 \
    -Wall ${HOME}/Documents/git/resist/code/test.c \
    -L${HOME}/anaconda3/envs/myenv/lib/python3.9/config-3.9-x86_64-linux-gnu \
    -L${HOME}/anaconda3/envs/myenv/lib \
    -lcrypt \
    -lpthread \
    -ldl \
    -lutil \
    -lm \
    -lpython3.9 \
    -Xlinker \
    -export-dynamic \
    -o ${HOME}/Documents/git/resist/code/test

```

I can’t tell whether this is a problem with how I’m grabbing the Python library (i.e., `-lpython3.9`) or something else. I pulled most of these commands from `python3.9-config --cflags` and `python3.9-config --ldflags` after I activated `myenv`:

```bash
(base) ~$ conda activate myenv

(myenv) ~$ python3.9-config --cflags
-I${HOME}/anaconda3/envs/myenv/include/python3.9 -I${HOME}/anaconda3/envs/myenv/include/python3.9 -Wno-unused-result -Wsign-compare -march=nocona -mtune=haswell -ftree-vectorize -fPIC -fstack-protector-strong -fno-plt -O3 -ffunction-sections -pipe -isystem ${HOME}/anaconda3/envs/myenv/include -fdebug-prefix-map=/opt/conda/conda-bld/python-split_1649141344976/work=/usr/local/src/conda/python-3.9.12 -fdebug-prefix-map=${HOME}/anaconda3/envs/myenv=/usr/local/src/conda-prefix -I${HOME}/anaconda3/envs/myenv/include -DNDEBUG -O3 -Wall

(myenv) ~$ python3.9-config --ldflags
-L${HOME}/anaconda3/envs/myenv/lib/python3.9/config-3.9-x86_64-linux-gnu -L${HOME}/anaconda3/envs/myenv/lib -lcrypt -lpthread -ldl -lutil -lm -lm 

```

---

<div class="post-metadata">

**Author:** ![sweller](https://avatars.discourse-cdn.com/v4/letter/s/c2df01/32.png) [@sweller](https://forum.anaconda.com/u/sweller)\
**Post date:** [June 22, 2022, 10:18pm UTC](https://forum.anaconda.com/t/calling-python-from-c-error-loading-shared-libraries/25861/2 "2022-06-22T22:18:28Z")

</div>

Hello,

I think you need to set the environment variable ‘LD\_LIBRARY\_PATH’ in your linux environment so that it can find your python library, since it doesn’t exist in the default location for C libraries.

Try setting: export LD\_LIBRARY\_PATH=/anaconda3/envs/myenv

You may also need to add to the existing setting of this env variable.

Then try rerunning your code.

---

<div class="post-metadata">

**Author:** ![jjameson](https://avatars.discourse-cdn.com/v4/letter/j/80bc00/32.png) [@jjameson](https://forum.anaconda.com/u/jjameson)\
**Post date:** [June 23, 2022, 7:21pm UTC](https://forum.anaconda.com/t/calling-python-from-c-error-loading-shared-libraries/25861/3 "2022-06-23T19:21:50Z")

</div>

OK, so I set the `LD_LIBRARY_PATH` environment variable in my environment.

```bash
~$ export LD_LIBRARY_PATH=~/anaconda3/envs/myenv

~$ echo $LD_LIBRARY_PATH
${HOME}/anaconda3/envs/myenv

```

I then built the C program as shown in the OP. After it built, I tried to run the program:

```bash
~$ ./test
./test: error while loading shared libraries: libpython3.9.so.1.0: cannot open shared object file: No such file or directory

```

So, it appears that I’m still getting this error. Should I set this variable in my `.bashrc` file?

---

<div class="post-metadata">

**Author:** ![jjameson](https://avatars.discourse-cdn.com/v4/letter/j/80bc00/32.png) [@jjameson](https://forum.anaconda.com/u/jjameson)\
**Post date:** [June 23, 2022, 7:39pm UTC](https://forum.anaconda.com/t/calling-python-from-c-error-loading-shared-libraries/25861/4 "2022-06-23T19:39:58Z")

</div>

The fix is to use the `lib` folder within the virtual environment.

```auto
~$ export LD_LIBRARY_PATH=~/anaconda3/envs/myenv/lib

```

This solved the problem (of course, now I’m getting a seg fault…)