[vox-tech] Mystery Segmentation Faults: grep and sed

[Peter Jay Salzman]

On Tue 28 Dec 04, 12:29 PM, Dylan Beaudette <dylan at iici.no-ip.org> said:
> 
> Thanks for the info Pete! I haven't actually used strace before, and only
> thought about it from reading the vox-tech list!
 
strace is the most underrated tool.  Mike Simons suggested it to me once, a
long time ago, and I've been a fan of it ever since.  Just to parse:

-ff means "if a child is spawned, follow it".  Each child gets its own log
   file (if you're writing to a log file).

-s means "increase the string size".  strace will cut down on string size
   to save output lines.  This can be used to increase it.

Also, it's usually safe to grep out calls to mmap/munmap, but in your case,
I suppose that wouldn't have been wise, what with grep causing problems.  ;)

ltrace, which is nearly as useful as strace, traces library calls instead of
system calls.  As you can imagine, there's less output, but sometimes it's
useful to see which *library* call is failing rather than system call.

Great set of tools.

> on a whim i restarted my machine, and now all is well! i can't really
> explain why that would fix something like that, but i sure am happy to
> have a functioning system back.
 
DOH!!!  That's the kind of thing we don't want the newbies to hear.  ;-)

If your C library got upgraded, who knows what kind of voodoo magic goes on?
I've always found it amazing that we're not told to reboot after libc gets
upgraded when you consider that everything that runs uses the old C library,
and everything that will run uses the new.

A testament to a well designed system.

> i cross-posted to the debian-ppc list, and i will report back on any
> findings!
 
Yeah -- please do.  I'd be interested in hearing anything you learn.

Pete

-- 
The mathematics of physics has become ever more abstract, rather than more
complicated.  The mind of God appears to be abstract but not complicated.
He also appears to like group theory.  --  Tony Zee's "Fearful Symmetry"

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