Allow for overriding all other machine-ids which may be present on
the system using a kernel command line systemd.machine_id or
--machine-id= option.
This is especially useful for network booted systems where the
machine-id needs to be static, or for containers where a specific
machine-id is wanted.
And remove machine-id-commit as separate binary.
There's really no point in keeping this separate, as the sources are
pretty much identical, and have pretty identical interfaces. Let's unify
this in one binary.
Given that machine-id-commit was a private binary of systemd (shipped in
/usr/lib/) removing the tool is not an API break.
While we are at it, improve the documentation of the command substantially.
This also allows us to drop build.h from a ton of files, hence do so.
Since we touched the #includes of those files, let's order them properly
according to CODING_STYLE.
This patch removes includes that are not used. The removals were found with
include-what-you-use which checks if any of the symbols from a header is
in use.
getopt is usually good at printing out a nice error message when
commandline options are invalid. It distinguishes between an unknown
option and a known option with a missing arg. It is better to let it
do its job and not use opterr=0 unless we actually want to suppress
messages. So remove opterr=0 in the few places where it wasn't really
useful.
When an error in options is encountered, we should not print a lengthy
help() and overwhelm the user, when we know precisely what is wrong
with the commandline. In addition, since help() prints to stdout, it
should not be used except when requested with -h or --help.
Also, simplify things here and there.
This makes it possible to initialize the /etc/machine-id file on an
arbitrary filesystem hierarchy. This helps systems that wish to run
this at image creation time in a subdirectory, or from initramfs before
pivot-root is called.
[tomegun: converted to using _cleanup_free_ macros]
