Dear all,
I tried starting background processes with lxc-attach and found strange
behaviour in Ubuntu Xenial (both container and host).
When I start lxc-attach without command and type my command in shell, it
waits for background process to end before completing the exit:
root@host:~# lxc-attach -n test
root@test:~# sleep 10 &
[1] 14607
root@test:~# exit
# hangs here for 10 seconds
root@host:~#
When I do it with nohup it works as indended: no wait, process continues
in the background:
root@host:~# lxc-attach -n test
root@test:~# nohup sleep 10 &
[1] 14621
nohup: ignoring input and appending output to 'nohup.out'
root@test:~# exit
root@host:~# lxc-attach -n test -- pgrep sleep
14621
root@host:~#
When I specify command in lxc-attach arguments or pass it
non-interactively, background process gets killed, even with nohup! (I
wonder what signal it gets.) There're no hangs below:
root@host:~# lxc-attach -n test -- bash -c 'nohup sleep 10 &'
root@host:~# echo 'nohup sleep 10 &' | lxc-attach -n test
root@host:~# lxc-attach -n test -- pgrep sleep
root@host:~#
Finally, nohup bash works:
root@host:~# lxc-attach -n test -- nohup bash -c 'sleep 10 &'
nohup: appending output to 'nohup.out'
root@host:~# echo 'sleep 10 &' | lxc-attach -n test -- nohup bash
nohup: ignoring input and appending output to 'nohup.out'
root@host:~# lxc-attach -n test -- pgrep sleep
14732
14734
root@host:~#
I wonder if this is intended or should be reported as a bug? I guess
this is somehow related to missing parent, right?
root@host:~# uname -a
Linux host 4.4.0-78-generic #99-Ubuntu SMP Thu Apr 27 15:29:09 UTC
2017 x86_64 x86_64 x86_64 GNU/Linux
root@host:~# lsb_release -a
No LSB modules are available.
Distributor ID: Ubuntu
Description: Ubuntu 16.04.2 LTS
Release: 16.04
Codename: xenial
--
With Best Regards,
Marat Khalili
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