# execute\_process: how to pass argument to python script
**URL:** https://discourse.cmake.org/t/execute-process-how-to-pass-argument-to-python-script/4999
**Category:** Usage
**Created:** [February 14, 2022, 3:22pm UTC](https://discourse.cmake.org/t/execute-process-how-to-pass-argument-to-python-script/4999 "2022-02-14T15:22:57Z")
**Posts on this page:** 9
**Page:** 1
### Author:  [@jwuttke](https://discourse.cmake.org/u/jwuttke)
#### Post date: [February 14, 2022, 3:22pm UTC](https://discourse.cmake.org/t/execute-process-how-to-pass-argument-to-python-script/4999/1 "2022-02-14T15:22:58Z")
```auto
execute_process(COMMAND ${Python3_EXECUTABLE} my_script.py my_arg)
```
doesn’t work as intended: `my_script.py` is executed, but does not see the argument `my_arg`.
Whereas on the command line
```auto
$ python3 my_script.py my_args
```
does work.
As a minimal example, suppose `my_script.py` is
```auto
import sys
print("my_script found argument", sys.argv[1])
```
---
### Author:  [@ben.boeckel](https://discourse.cmake.org/u/ben.boeckel)
#### Post date: [February 14, 2022, 5:19pm UTC](https://discourse.cmake.org/t/execute-process-how-to-pass-argument-to-python-script/4999/2 "2022-02-14T17:19:51Z")
This works locally:
```auto
% cmake -P run.cmake
-- Found Python3: /usr/bin/python3.9 (found version "3.9.10") found components: Interpreter
my_script found argument my_arg
% cat my_script.py
import sys
print("my_script found argument", sys.argv[1])
% cat run.cmake
find_package(Python3 REQUIRED COMPONENTS Interpreter)
execute_process(COMMAND ${Python3_EXECUTABLE} my_script.py my_arg)
```
Can you provide a fuller example that shows the problem?
---
### Author:  [@jwuttke](https://discourse.cmake.org/u/jwuttke)
#### Post date: [February 15, 2022, 11:05am UTC](https://discourse.cmake.org/t/execute-process-how-to-pass-argument-to-python-script/4999/3 "2022-02-15T11:05:39Z")
Thank you very much, Ben.
Things didn’t work in my more complex code because I confused upper and lower case in a variable name.
Apologies, Joachim
---
### Author:  [@Nguyen\_Khuong](https://discourse.cmake.org/u/Nguyen_Khuong)
#### Post date: [November 3, 2023, 3:40pm UTC](https://discourse.cmake.org/t/execute-process-how-to-pass-argument-to-python-script/4999/4 "2023-11-03T15:40:49Z")
Hello everyone,
I faced issue when send back argument from python to Cmake I used
os.environ[“MY\_DATA”] = ‘2’
print(os.environ[“MY\_DATA”])
and I read the env variable in Cmake was
set(env $ENV{MY\_DATA})
message(“Helloo Python your value is : ${env}”)
It not work , Can someone explain for me why
---
### Author:  [@ben.boeckel](https://discourse.cmake.org/u/ben.boeckel)
#### Post date: [November 3, 2023, 4:42pm UTC](https://discourse.cmake.org/t/execute-process-how-to-pass-argument-to-python-script/4999/5 "2023-11-03T16:42:06Z")
Can you provide the relationship between these two snippets of code? Is the Python script doing the `os.environ` setting launching CMake somehow? Can you share that?
---
### Author:  [@Nguyen\_Khuong](https://discourse.cmake.org/u/Nguyen_Khuong)
#### Post date: [November 3, 2023, 5:13pm UTC](https://discourse.cmake.org/t/execute-process-how-to-pass-argument-to-python-script/4999/6 "2023-11-03T17:13:18Z")
Hi Ben ,
Thanks for reply
For 2 snippet code I wanted trial to send a message from Python to CMake parents , when it call to Python I trial to export an env variable by Python to use in CMake for other purpose. I used with excute\_process to call Python script in CMake parents and message to print value Python return back . But it was not work
---
### Author:  [@ben.boeckel](https://discourse.cmake.org/u/ben.boeckel)
#### Post date: [November 3, 2023, 5:53pm UTC](https://discourse.cmake.org/t/execute-process-how-to-pass-argument-to-python-script/4999/7 "2023-11-03T17:53:25Z")
A child process cannot set the environment of the parent process, so a Python script setting its environment has no effect on the CMake process calling it via `execute_process`.
---
### Author:  [@Nguyen\_Khuong](https://discourse.cmake.org/u/Nguyen_Khuong)
#### Post date: [November 3, 2023, 10:49pm UTC](https://discourse.cmake.org/t/execute-process-how-to-pass-argument-to-python-script/4999/8 "2023-11-03T22:49:56Z")
Thanks for your reply Ben .
Are there anyway Python scripts can export env for other scripts use or it just only set its env and other scripts can’t see ? I used to set env variable in CMake and shell. Python scripts use env (export env in shell and set env $ENV{env} in CMake) . I just trial some way to export env variables from Python.
---
### Author:  [@ben.boeckel](https://discourse.cmake.org/u/ben.boeckel)
#### Post date: [November 6, 2023, 11:25pm UTC](https://discourse.cmake.org/t/execute-process-how-to-pass-argument-to-python-script/4999/9 "2023-11-06T23:25:49Z")
The environment can only be modified for the currently running processes and new processes started (via passing them to the `execve` or `CreateProcess` family of APIs).