How do I run nohup as a different user without spawning two processes?

Question

I'm trying to nohup a command and run it as a different user, but every time I do this two processes are spawned.

For example:

$ nohup su -s /bin/bash nobody -c "my_command" > outfile.txt &

This definitely runs my_command as nobody, but there's an extra process that I don't want to shown up:

$ ps -Af
.
.
.
root ... su -s /bin/bash nobody my_command
nobody ... my_command

And if I kill the root process, the nobody process still lives... but is there a way to not run the root process at all? Since getting the id of my_command and killing it is a bit more complicated.

javdev · Answer 1 · 2016-04-22T07:59:46.280

14

This could be achieved as:

su nobody -c "nohup my_command >/dev/null 2>&1 &"

and to write the pid of 'my_command' in a pidFile:

pidFile=/var/run/myAppName.pid
touch $pidFile
chown nobody:nobody $pidFile
su nobody -c "nohup my_command >/dev/null 2>&1 & echo \$! > '$pidFile'"

edited Apr 22 '16 at 07:59

answered Jun 03 '15 at 08:02

javdev

794
2
10
23

score 4 · Answer 2 · edited Mar 21 '13 at 18:09

4

nohup runuser nobody -c "my_command my_command_args....." < /dev/null >> /tmp/mylogfile 2>&1 &

edited Mar 21 '13 at 18:09

Igor

33,276
14
79
112

answered Mar 21 '13 at 17:50

user2196349

41
2

what's the `runuser` bit? – K3---rnc Apr 15 '14 at 23:10
do a `man runuser`. its not an argument of nohup but its own separate command a lot like su – Rooster Jun 03 '14 at 16:00

Wangwang · Answer 3 · 2017-09-26T13:52:00.543

2

If the user with nologin shell, run as follows:

su - nobody -s /bin/sh -c "nohup your_command parameter  >/dev/null 2>&1 &"

Or:

runuser - nobody -s /bin/sh -c "nohup your_command parameter  >/dev/null 2>&1 &"

Or:

sudo su - nobody -s /bin/sh -c "nohup your_command parameter  >/dev/null 2>&1 &"

sudo runuser -u nobody -s /bin/sh -c "nohup your_command parameter  >/dev/null 2>&1 &"

edited Sep 26 '17 at 13:52

answered May 16 '17 at 06:54

Wangwang

157
2

score 1 · Answer 4 · answered Jul 30 '12 at 19:02

You might do best to create a small script in e.g. /usr/local/bin/start_my_command like this:

#!/bin/bash
nohup my_command > outfile.txt &

Use chown and chmod to set it to be executable and owned by nobody, then just run su nobody -c /usr/local/bin/start_my_command.

score 0 · Answer 5 · answered Jul 02 '20 at 19:59

A note on running this on a session, is that if you run in background, there is a job associated with the session, and background jobs may be killed (the su -c gets around this).

To disassociate the process from the shell (so you can exit the shell but keep the process running), use disown.

How do I run nohup as a different user without spawning two processes?

5 Answers5

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