[lfs-dev] Systemd - KillUserProcesses=yes (Was: Re: [blfs-dev] Two hints about building firefox-47.0.1 and using screen with systemd-230)

DJ Lucas dj at linuxfromscratch.org
Mon Aug 1 19:53:27 PDT 2016



On 07/31/2016 01:06 PM, Tim Tassonis wrote:
> On 07/31/16 17:48, DJ Lucas wrote:
>>
>>
>> On July 30, 2016 8:55:40 PM CDT, "Douglas R. Reno"
>> <renodr at linuxfromscratch.org> wrote:
>>
>>>
>>> I'll make the change to /etc/systemd/logind.conf with the update to
>>> systemd-231 that I am working on.
>>
>>
>> Let's not do that by default. Rather, put text containing an
>> explanation, and the command with a nodump attribute in LFS, and add a
>> note in BLFS on the screen page (only real consumer we have).
>
>
> As far as I understand, also nohup from coreutils is concerned.
>

Michael and Tim BCC'd (not sure if you are sub'd to LFS-Dev).

So I wanted to give this a bit more of a fair shake than simply not 
going against upstream. I spent more than a few hours sorting through 
systemd sucks/rules flame fests to find the occasional intelligent 
argument for or against the 230 change in default.

I haven't changed my request to leave it at default. In short, the 
default is now a restrictive model vs. the previous permissive. The well 
written arguments both for, and against, are all essentially the same. 
To paraphrase: It fixed (or broke) 30 some-odd years of 
nohup/daemon()/setsid() being virtually unrestricted.

So there are four different ways to turn it off in various contexts. 
Compile time (break/fix semi-permanently), config file (break/fix 
temporarily), user session (loginctl enable-linger [user] (break/fix for 
one user)), or at runtime via systemd-run. The systemd-run functionality 
was added as the replacement method to corral the former free for all. 
This essentially leaves it up to the user or system admin rather than 
allowing random binaries to run forever.

As Tim mentioned, nohup is broken (by design) when enabled (the 
default). Other threads have suggested removing nohup and/or symlinking 
nohup->systemd-run, but I also don't think we should go so far as to 
disable installation of nohup (it still works when the new functionality 
is disabled using three of the methods above).

https://www.freedesktop.org/software/systemd/man/loginctl.html
https://www.freedesktop.org/software/systemd/man/systemd-run.html

Instead, I'd like to see another sect2 added to 7.10 discussing the new 
functionality, meeting the official primary goal of LFS. I'll be happy 
to write it if agreed upon.

Thoughts?

--DJ

Way OT: They were all wrong! It was forty something years. FYI, just to 
save the time since I already stumbled across somebody else 
"justinsaccount" who had the itch, buried deep in one of the flame 
fests...42 years in the case of nohup (officially appeared in RV5 in 
1974, though one early version is dated 1973). Names like Denis Ritchie, 
Bill Joy, Ken Thompson... :-)
https://github.com/dspinellis/unix-history-repo.git
Kind of fun to dig through. :-)





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