Do I really need to use nohup?

Question

I would like to let run my script on background on my server. I red about nohup. I have my script.py. I run it like this:

python3 script.py&

It runs on background even when I close terminal. The script write numbers to file /tmp/aaa.txt every second, started from 0. I disconnect from server and reconnect to it and sow that there is numbers over 3000 (over 50 minutes). So my question is, do I really need to use nohup? If yes/no why?

# hostnamectl                                                                                                                                                                                                          
   Static hostname: my-server                                                                                                                                                                                                          
         Icon name: computer-vm                                                                                                                                                                                                              
           Chassis: vm                                                                                                                                                                                                                       
        Machine ID: XXXX                                                                                                                                                                                         
           Boot ID: XXXX                                                                                                                                                                                         
    Virtualization: vmware                                                                                                                                                                                                                   
  Operating System: Ubuntu 16.04.3 LTS                                                                                                                                                                                                       
            Kernel: Linux 4.4.0-116-generic                                                                                                                                                                                                  
      Architecture: x86-64

My script script.py:

import time

i = 0

while True:
  f = open('aaa.txt', 'a+')
  f.write('Doing somethign: {0}\n'.format(i))
  f.close()
  i = i + 1
  time.sleep(1)

You don't need to use `nohup` if the script ignores the `HUP` signal. Does it? — Kusalananda, Jun 25 '18 at 20:51
I do not configure anything, how can I check it? I added output of my `script.py`. — dorinand, Jun 25 '18 at 20:54

score 4 · Answer 1 · answered Jun 25 '18 at 21:32

4

The action is controlled by the bash option huponexit . Check to see what it is set to, if set to "on" it will send a sighup to all child processes on exit. If not, it should keep running.

$ shopt | grep huponexit
huponexit       off

answered Jun 25 '18 at 21:32

Joe M

866
4
6

Hi, I can see the same output as you have, thank you for your explanation. – dorinand Jun 25 '18 at 21:41

Do I really need to use nohup?

1 Answers1