Re: systemdq

[Greg Wooledge <wooledg@eeg.ccf.org>]

On Sat, Dec 28, 2019 at 02:57:40PM -0700, Charles Curley wrote:
> Debian (not rasbian) seems to put sshd into place at installation time.
> 
> charles@hawk:~$ locate sshd.service
> /etc/systemd/system/sshd.service
> /var/lib/systemd/deb-systemd-helper-enabled/sshd.service
> charles@hawk:~$
> 
> The second one has to be there. The first is optional and overrides the
> second.

I know this has been mentioned once in this gargantual sprawling
thread of lies and incompetence, but I think it needs repeating.

Debian (and probably Raspbian also, but I have no way to know for sure)
ships a unit file named

  ssh.service

Note that there is no 'd' here.

Within this unit file, there is the following line:

  Alias=sshd.service

This means that SOME OF THE TIME, you can get away with calling it
"sshd.service" -- for example when you try to start or stop it.

However, the Alias name does not always work.  Sometimes you must
use the actual name of the unit -- for example, if you try to create
a drop-in directory under /etc/systemd/service/ to tweak it.

Please trust me: you DO NOT under any circumstances want to create a
drop-in directory using the Alias name.  Bad shit happens.  I found
this out the hard way.

Some of you have already observed that there's an
/etc/systemd/system/sshd.service in Debian.  Let's take a closer look
at that:

lrwxrwxrwx 1 root root 31 Apr 10  2017 /etc/systemd/system/sshd.service -> /lib/systemd/system/ssh.service

It's not a file.  It's a symlink, and that symlink points to the REAL
unit file with the name "ssh.service" (no "d").  This is what the Alias
line does.  It creates this alternatively-named reference ("sshd.service")
that you can use to start and stop the service, but NOT to configure
it.

There's been a lot of bad advice given in this thread.  It's extremely
hard to undo that.  All I can do is try to point out the truth and the
falsehoods, and hope that people will update their mental caches.

And the moral of all of this is:

  DO NOT POST RASPBIAN ISSUES IN DEBIAN-USER.