os.getenv returns empty output - python

问题

I am new to python and encountering some issues while executing os commands.

I have set my environment variables like as shown below

SPARK_HOME = '/opt/spark'
HAIL_HOME  = '/opt/hail/hail'

When I type os.getenv('SPARK_HOME'), I get the below output

'/opt/spark/'

But when I type os.getenv('HAIL_HOME'), I get blank output

Please note that I type the above two commands from a virtual environment using jupyter notebook.

1. Why it works for spark and returns empty for hail

Can guide me with this issue?

回答1:

Based on our discussion on chat, identified several issues.

Variable setting is confused with env variable setting. So correct way to set them should be like:

os.putenv('SPARK_HOME', '/opt/spark')
os.putenv('HAIL_HOME', '/opt/hail/hail')

Even the mistaken env variable set attempts, SPARK_HOME shows the correct value because jupyter process inherits that variable from the shell.

来源：https://stackoverflow.com/questions/62530145/os-getenv-returns-empty-output-python