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From Greg Ames <grega...@remulak.net>
Subject dumps on Linux: some progress
Date Thu, 09 Aug 2001 15:10:03 GMT
Last nite I figured out how to get a core dump of a threaded server on
Linux when it seg faults.  After Justin pointed out that he's seen dumps
w/threaded, I noticed that I had a few old dumps in my home directory,
and one in root's home directory, but nothing my configured
CoreDumpDirectory (writeable by everybody w/the sticky bit set).

I had "User nobody" and "Group nobody" in my config file, to match
daedalus as closely as possible.  hmmmm..."nobody" doesn't have a home
directory.  So I created "webuser" which does have a home directory, and
only belongs to its own group.  Changed the config file to use this
user/group, fired up threaded with mod_cgid, did an "apachectl restart",
and voila! a coredump appeared in my CoreDumpDirectory.  

I still don't know exactly what the deal is here (i.e., is it important
that "webuser" has a home dir?  is Mandrake's security stuff or Linux
itself doing something to "nobody"? does this have anything to do with
using threads?) but thought it might be useful to other folks.

Still nothing in the error log.  This shouldn't be a surprise - we don't
have code that logs when the parent itself seg faults.

Thanks to Justin for letting us know that core dumps are possible
w/threaded on Linux, and to Ben whose Horse book is where I got the idea
for "webuser".

Greg

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