[McIDAS #OMS-336835]: 20160801: xcd_run modification for LDM-6.13.x

Hi Christian,

On Friday, July 29 you posted the following to ldm-users:
> This is the same for me I had to revert to LDM 6.12.6 because the xcd
> process would quit after about one day.

We now know how/why your McIDAS-XCD decoding was being "killed"
when running an LDM-6.13.x version of the LDM.  In order to support the
a logging package, a new script was included in the distribution, and
that script sends a SIGHUP to the LDM process group.  This means that
the McIDAS-XCD MONITORing action (the 'EXEC util/xcd_run MONITOR'
line in ~ldm/etc/ldmd.conf) is now getting a HUP signal, and the program
that the xcd_run script 'exec's, 'startxcd.k', is not instrumented to
ignore signals, so it is exiting.  'startxcd.k' is the McIDAS command
that runs and keeps running XCD data monitors, and the data monitors
run one or more decoding tasks.  So, the cause of the XCD decoding
exiting is a cron entry that is rotating your LDM log file.

A fix for this situation is currently being tested here in Unidata, but
there is a small modification that you can make to the EXEC line in your LDM
configuration file, ~ldm/etc/ldmd.conf, if you want to upgrade to LDM-6.13.3
right now:

change:

exec    "util/xcd_run MONITOR"

to:

exec    "nohup util/xcd_run MONITOR"

Putting the 'nohup' in front of 'util/xcd_run' (or wherever you have
your setup for) will insure that the script 'xcd_run' will not receive
the HUP signal, and 'startxcd.k' which is 'exec'ed in 'startxcd.k'
will also never see the signal, so it won't react to the SIGHUP
that is sent by the LDM file rotation script.

Just thought you should know your options...

Cheers,

Tom
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