Verbose output from Daemons on startup

[suvayu ali]

On Mon, Oct 31, 2011 at 05:22, T.C. Hollingsworth
<tchollingsworth at gmail.com> wrote:
> Usually its easier to debug daemon problems by just running them on
> the command line.  Look for the ExecStart line in
> /lib/systemd/system/<name>.service or if it uses classic initscripts
> check the corresponding file in /etc/init.d for the command that is
> run.  That way you can easily run it through strace if you need to.
>
> That being said, on Fedora 16, systemd redirects stdout and stderr to
> syslog, so you can view the output from the daemons in
> /var/log/messages.  Unfortunately, IIRCC F15 systemd does not do this,
> so edit /etc/systemd/system.conf and add a line that says
> "DefaultStandardOutput=syslog".  The next time you boot, all daemons'
> stdout and stderr will be stored in syslog so you can view it
> afterward, either in /var/log/messages or with a viewer like
> KSystemLog.  Messages from the kernel are also stored there, so you
> can see everything in one place.
>
> You can also set DefaultStandardOutput to "syslog+console" to have it
> output to the console as well, but that can be problematic because
> systemd starts many services in parallel.  (If you decide to do that,
> make sure to remove "rhgb quiet" from your kernel command line as well
> so Plymouth gets out of the way and kernel messages are printed to the
> console also.)
>
> It's also rather easy to run systemd native services through strace,
> just run copy the .service file from /lib/systemd/system to
> /etc/systemd/system and append strace the command on the ExecStart
> line.  When you're done, just rm the file in /etc and the one in /lib
> will take back over.  Classic initscripts are a little harder:  you
> have to find the appropriate line in the script and change it, and
> then change it back when you're done.
>

That is an amazingly clear "systemd debugging howto". Thanks a lot, I
have been putting off debugging ddclient because of my unfamiliarity
with systemd. Not any more. :)

PS: Have you considered putting this on the fedoraproject wiki?

-- 
Suvayu

Open source is the future. It sets us free.