I was looking for the explanation for the exclamation mark in the text,
and couldn't find it, searching for "!". Let's make this easier, and
indicate the character meant.
As described in #15603, it is a fairly common setup to use a fqdn as the
configured hostname. But it is often convenient to use just the actual
hostname, i.e. until the first dot. This adds support in tmpfiles, sysusers,
and unit files for %l which expands to that.
Fixes#15603.
The hack with getparent().txt is not very pretty, but the whole
thing seems to work well enough. It is useful to figure out whihc
specifiers are supported where.
We probably can migrate even more, but for now let's just migrate those
which have the 1:1 identical text everywhere.
(Also, let's add the % entry to all specifier tables)
When wrong element types are used, directives are sometimes placed in the wrong
section. Also, strip part of text starting with "'", which is used in a few
places and which is displayed improperly in the index.
The synopsis section would describe config file paths, but not their
syntax. Let's add a short table that so that it's possible to quickly
remind oneself what the different letter mean.
The "include" files had type "book" for some raeason. I don't think this
is meaningful. Let's just use the same everywhere.
$ perl -i -0pe 's^..DOCTYPE (book|refentry) PUBLIC "-//OASIS//DTD DocBook XML V4.[25]//EN"\s+"http^<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"\n "http^gms' man/*.xml
