Patrick O'Callaghan pocallaghan@gmail.com writes:
On Sat, 2014-07-05 at 22:07 -0400, Garry T. Williams wrote:
The systemd(1) manual page uses the term "entity" -- not object to refer to units. And it says units encapsulate various objects. Perhaps this is the source of confusion?
The word "entity" is not used anywhere in the systemd(1) man page. The plural "entities" is used exactly once, in the phrase "systemd provides a dependency system between various entities called "units" of 12 different types". So apparently entity==unit.
There could be other entities somewhere that aren't units and aren't mentioned in the man page. Or perhaps they are but aren't called that.
However, according to [1], "entity" is a synonym for "unit". So what exactly does the quoted sentence from the man page try to explain?
[1]: http://thesaurus.com/browse/unit
The term "object" is used twice. Once is in reference to "file system objects" which I assume has the usual meaning. The other is in "Units encapsulate various objects that are relevant for system boot-up and maintenance".
So to sum up: systemd manages dependency relations between entities called units. Units encapsulate objects in 12 different ways. Objects are <insert hand-waving here>
It's much simpler: "systemd provides a dependency system between <insert hand-waving here> which are/is encapsulated in 12 different types".
So what does it actually do?
And I can only guess that it's called "systemd" because it provides a "system" and is a daemon. But is it a daemon? Looking at [2], it is not because it's controlled by a user (through systemctl and journalsomething and perhaps other things I don't know about).
Actually, it's more like an MCP, if you've seen Tron.
[2]: https://en.wikipedia.org/wiki/Daemon_(computing)
I repeat that I am not attacking systemd here, I'm criticizing the way it's described. It may seem perfectly clear to those who already understand it, but it's not at all clear to those who are used to something different.
The documentation is just badly written. What do you expect when "disabled" means something like "not so much enabled" and "mask" means "disabled"? I made a bug report about that, and they decline to even fix a simple thing like that.