Debugging a core dump

If a program crashes with a core dump then, it is easy to debug and find the last internal state of the program. When we run multiple programs or threads, then it is difficult to find which core was generated by which process. To resolve this, there are a few settings available in /proc, which will help us to add more detail in the core file name.

Support available from Kernel v2.4. Setting '1' to this file, will generate a core file with PID. For example: core.1234
/proc/sys/kernel/core_uses_pid

Support available from Kernel v2.5. This file provides more control to form the core file name.
/proc/sys/kernel/core_patten

This is very similar to setting the core_uses_pid option.
echo "core.%p" > /proc/sys/kernel/core_pattern

By setting this value, core file will be generated with the following details: executable filename, PID of the dumped process and number of the signal causing the dump.
echo "core.%e.%p.%s" > /proc/sys/kernel/core_pattern

More useful options are explained in the proc man page.

This Tech Tip was brought to us by Bharathi in Chennai, India. Thanks, Bharathi!

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