We are saying in public that the protocl is stable and can be easily
reimplemented, so provide an example doing so in the documentation,
license as MIT-0 so that it can be copied and pasted at will.
"submitted" is already used in the description of FDNAME=.
Let's use that instead of "stored" for FDPOLL= too, to make
it more clear that it's a per-submission/per-fdset setting.
In principle, arbitrary notifications may be sent via sd_notify. But in
practice, this is not useful at all, since the manager only accepts
notifications from services and ignores anything except a few specific
ones. The others will be logged if debugging is enabled. OTOH, the manager
produces EXIT_STATUS, but nothing in systemd looks at it, which is rather
confusing.
So remove the recommendation to use X_ prefixes, and instead say that other
messages will be ignored. Also, mention that mkosi uses this. Having an example
may be useful to understand what is going on.
Strangely, this is the first reference to mkosi in our man pages. Even more
strangely, debian is the only place which hosts the mkosi man page (among
the sites we have definitions for), so I linked to that version.
This tries to add information about when each option was added. It goes
back to version 183.
The version info is included from a separate file to allow generating it,
which would allow more control on the formatting of the final output.
Doesn't really matter since the two unicode symbols are supposedly
equivalent, but let's better follow the unicode recommendations to
prefer greek small letter mu, as per:
https://www.unicode.org/reports/tr25
I guess it was only a question of time until we need to add the final
frontier of notification functions: one that combines the features of
all the others:
1. specifiying a source PID
2. taking a list of fds to send along
3. accepting a format string for the status string
Hence, let's add it.
