nohup

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$ nohup sh ./test.sh &
$ nohup test.sh &

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$ nohup test.sh > test.log 2>&1 &

• 0 - stdin (standard input)
• 1 - stdout (standard output)
• 2 - stderr (standard error)

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$ nohup python -u test.py > test.log 2>&1 &

Sometimes I find that nohup.out does not show what is printed in the python program. This is because python’s output is buffered, so nohup.out doesn’t see the output right away. python has a -u parameter that makes python not enable buffering. Change it to the following command and you’re good to go!

setid

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# setsid sh ./test.sh

This method makes the running process run as root, which is somewhat of a security risk.

trap

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#!/bin/bash
trap "" HUP
while true;do
    date >> /root/test.txt
    sleep 1
done

screen

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$ screen sh test.sh