[SOLVED] Nohup doesn't print to stdout until termination

Issue

I have a Python script like the following:

#!/usr/bin/env python

print("Start")
sql = get_sql_from_file(...)
# The following function takes a long time to run
execute_oracle_driver(sql)
print("Finished")

I execute it with:

(my-env) $ time nohup python script.py &

Then I check if there's any initial output, but nothing:

(my-env) $ cat nohup.out
(my-env) $ 

I would at least expect to see "Start" after no more than a few seconds. Even after waiting a few minutes, then killing it, I get no output. If possible, how can I fix this?

Solution

Output is buffered by default, so you would need to ensure that the output is flushed; otherwise, no output will be seen in nohup.out until the end of the program. One way to do that is as follows:

print("Start", flush=True)

Answered By - Anthony Tuininga