import os.path

# Check if a file exist, return True/False
os.path.exists("test.txt")

# Check if a directory exist, return True/False, for >= python3.4
import pathlib
pathlib.Path("test").exists()

Source:
https://www.guru99.com/python-check-if-file-exists.html

When we want to use Unix command in python we can directly use os.system() to realize it. However, if we only want to return the output as a string, for example, return ls file names into a string, we need to use subprocess.check_out instead.

To note that, the output from subprocess.check_out() is a bytes object instead of a string, thus we need to further decode to transform into a string.

fileList = subprocess.check_output('ls someFolder/*', shell=True).decode('utf-8').strip().split('\n')

Source:
https://stackoverflow.com/questions/606191/convert-bytes-to-a-string

Check running servers:

jupyter notebook list

Stop running servers (both works):

jupyter notebook stop
kill $(pgrep jupyter)

Source:
https://github.com/jupyter/notebook/issues/1950
https://stackoverflow.com/questions/10162707/how-to-close-ipython-notebook-properly/32745046#32745046

In Jupyter Notebook, use the below command within the notebook to install packages in the current working environment. This is specifically useful when you are working in the notebook, and need to install new packages to the matching python version you are using.

!{sys.executable} -m pip install XXX

To run Unix command in python:

import os
os.system('your unix code')
os.system('ls')

Source:
https://code.tutsplus.com/articles/how-to-run-unix-commands-in-your-python-program–cms-25926

Unix syntax:

echo ${readIn_list[@]}
echo $var
python yourPython.py $var ${readIn_list[@]}

readIn_list = sys.argv[2:]

Source: https://unix.stackexchange.com/questions/519625/passing-bash-array-to-python-script