On Oct 31, 2011 2:54 AM, "suvayu ali" <firstname.lastname@example.org> wrote:
> On Mon, Oct 31, 2011 at 05:22, T.C. Hollingsworth
> <email@example.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?
I have marked this thread.* I hope T.C. is interested in writing something up, since he clearly has a better understanding than I.* If not, I will. This is great info, thanks!
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