I'm top-posting on a bottom-post thread, and I'm replying to myself to
retract what I said below. The executable I found,
/lib/systemd/systemd-udevd, did not come with the libsystemd0 package. It
was already there.

If someone knows how to tell if a library was used by a program, I would
like to learn how that is done. Thanks.

-fsr


On 07/20/2016 06:18 AM, fsmithred wrote:
> On 07/19/2016 06:10 PM, Rick Moen wrote:
>> Saying libsystemd0 'does something' merely because higher-layer GNOME
>> code probed it for a function and then decided to do or not do something
>> based on what it found (my high-confidence surmise about your gvfs
>> anecdote) entails very peculiar construing of the verb 'to do' -- and
>> I'm pretty sure hardly anyone else uses the verb quite that way.
>
>
> Oh, you must have missed my last report. Surely, you would agree that
> executing an executable file is doing something.
>
> For the past two years, people have been saying that libsystemd0 is just a
> library, and it does nothing if systemd is not installed or not running.
> I've been skeptical of such claims, but until yesterday, I wasn't sure.
> Neither one of those claims is accurate. Among the files that the
> libsystemd0 package provides, at least two of them are executable files.
> There may be more that aren't located in /lib/systemd/.
>
> Here it is again.
>
>> One more test - instead of 'chmod -R 000 /lib/systemd' I tried 'chmod -x
>> /lib/systemd/systemd-udevd' thus disabling an executable binary file that
>> libsystemd0 provides. Dropped to runlevel 1, ctrl-d to return to desktop,
>> and removable drives no longer appear on the desktop.
>
> I suppose it's possible that gvfs just checks for the executable bit on
> /lib/systemd/systemd-udevd and doesn't actually run that program, but I
> doubt that.
>
> To summarize: libsystemd0 runs its program(s) even when systemd is not
> installed.
>
> -fsr
>