Empty core dump file

[David Aldrich]

Hi

I am new to examining core dump files using gdb.  I am running Centos 5.5.

When my C++ program crashes with a segmentation fault I get an empty core dump file called core.13754.

I have previously executed:

ulimit -c unlimited

I built with -g.

Why might the core dump be empty?

Why does the filename include a number?

(/proc/sys/kernel/core_pattern contains just 'core').

Best regards

David