Crontab and python versions

[stsxbel]

Good day. Please help me figure this out. Ubuntu has 2 versions of python (3.6 and 3.9). Pymodbus (2.5.3 and 3.0) are installed via pip. So, when I run the script via the terminal, everything is ok, but when I run it via crontab (I specify to run it via python3.9), it takes the 2.5.3 library. How can I make it take the 3.0 library?

[Zensei]

You can make your python script executable, and inside your script you use the path to the python path you desire

For example I have this script that is pointing to the python version I want.

#!/usr/local/bin/python3

import socket

sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)

host = '192.168.2.34'
port = 443

def portscanner(port):
    # print(sock.connect_ex((host, port)))
    if sock.connect_ex((host, port)):
        print(f"For host {host}:{port} is closed")
    else:
        print(f"For host {host}:{port} is open")

portscanner(port)

Then I made the script executable and does it call it from crontab

[Larz60+]

You can use pyenv, and have a different version for each project,
See: pyenv Simple Python Version Management

[snippsat]

I run it via crontab (I specify to run it via python3.9), it takes the 2.5.3 library.

Specify full path in crontab.

which python3.9

Example output: /usr/bin/python3.9

Eg install pymodbus 3.0 to the correct Python version:

/usr/bin/python3.9 -m pip install pymodbus==3.0

Use the full path in crontab:

* * * * * /usr/bin/python3.9 /path/to/your_script.py

If this not works try using a virtual environment.

python3.9 -m venv /home/youruser/myenv
source /home/youruser/myenv/bin/activate
pip install pymodbus==3.0 

Crontab entry using full path to python in venv.

* * * * * /home/youruser/myenv/bin/python /path/to/your_script.py