Re: core issues



On Sun, Apr 08, 2001 at 02:40:25PM -0700 or thereabouts, Lee Johnson wrote:
> okay i understand that to get to bottom of core issues ( the application
> causing grief? ) i need to focus on core file
> and trace to application and write author blah blah....okay fine but how
> do i read the darn  core file? :)
> all i get is" ELF"

Core files are not nice ascii files. They are basically a dump of
"what was happening at the time" into a file and have lots of characters
that screw up programs like 'more' and 'less'. 

The way to get info out of them is to feed them to a debugger. For
GNOME, that's typically gdb, as other people posted. Or, with a
recent GNOME, you should be able to double-click on it in the file
manager and get bug-buddy starting and invoking gdb for you.

If you get lots of lines with question marks like this: 
(??) in (??)
...it means you have a "stripped" binary: one with all the debugging
stuff stripped out to make it smaller. This is common with stuff shipped
by distros. If you get lots of lines with 
function_name() in filename.something
...you have something much more useful. 

Never send the core file to an author. Send the output of gdb instead.
If however you get tons and tons of "(??) in (??)" messages, it may
not be too helpful. 

If all you want to do is work out "what program crashed" so you can
tell the right author to inform, then there is a command called simply
"file" which will tell you. I wonder whether that's what you used if
you got an output of "ELF"? 

$ file core
core: ELF 32-bit LSB core file of 'cat' (signal 3), Intel 80386, version 1
                                  ^^^^^
So there I core-dumped cat (deliberately, to get the syntax for you :))
One thing to know is that Netscape, which has occasionally been known
to create core files (just once in a while, la la la), shows up as a
"core file of 'ld.linux.so.2'" or something similar. If you get that,
your Linux kernel was not responsible; it was netscape :)

Some distros assume users do not want to see core files, and set a bash
shell option (ulimit) to make sure they never appear. 

Telsa




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