How to add an environment variable LD_LIBRARY_PATH to the python code and effective

[zjl767864079zjl]

I add LD_LIBRARY_PATH to the python code like:

test.py

import os
from ctypes import CDLL

os.environ['LD_LIBRARY_PATH'] = "/home/test/myfolder/pyfolder/ztools1226/lib"
print(os.environ)
s_dll_path = f"/home/test/myfolder/pyfolder/ztools1226/lib/libCityPlanParse.so"
dll_load = CDLL(s_dll_path)

I print the os.environ the LD_LIBRARY_PATH value already exists,but when I CDLL /home/test/myfolder/pyfolder/ztools1226/lib/libCityPlanParse.so report an error:
OSError: libCityPlanParse.so: cannot open shared object file: No such file or directory

But when I join in the command-line "export LD_LIBRARY_PATH=/home/test/myfolder/pyfolder/ztools1226/lib" before executing test.py,program execution ok.

So the environment variable I added in the code is not take effect.But I need to do that.How can I write about it to take effect?

My environment

python 3.8.3
Linux system

[avinash-218]

is there any solution for this issue

[duaneg]

Changes to LD_LIBRARY_PATH will not be effective after the program has started, as dlopen is implemented by the dynamic linker that loads the program, and it reads that environment variable at initial load time. It will not notice subsequent changes (although changes will affect any child processes that inherit the parent's environment).

This is nothing to do with python per se, it is just how Linux (and I assume other POSIX systems) work. The same applies if you use putenv and dlopen from C code, for example. You can work-around it by passing an absolute path to CDLL, setting LD_LIBRARY_PATH prior to running your main code in a wrapper script, and no doubt various other ways.

See here for more explanation: https://stackoverflow.com/questions/856116/changing-ld-library-path-at-runtime-for-ctypes/4326241.

This issue should be closed.