Re: Verbose output from Daemons on startup

[Pete Travis]

On Oct 31, 2011 2:54 AM, "suvayu ali" <fatkasuvayu+linux(a)gmail.com&gt;
wrote:
>  On Mon, Oct 31, 2011 at 05:22, T.C. Hollingsworth
>  <tchollingsworth(a)gmail.com&gt; 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!