Preparing for a core dump

Security enhancements on Linux-based platforms may prevent a core dump from being generated when you are expecting one. If you are using the core_on_error=1, core_on_error=2, or signal_regime tunables, you need to perform the following steps to override the security, and then run the application from which you require the core dump. (If you are using core_on_error=3, a core dump file will always be created, regardless of this security enhancement; follow the details in To create a core dump instead.)

1. Disable any size limitations that could stop the core dump file from being created in its entirety:

   ulimit -c unlimited

2. Specify the format and location in which the core dump is to be created - to create the core dump file in the format core.process-id, in the same directory as your application:

   echo "core.%p"> /proc/sys/kernel/core_pattern

   Note: This is only set for the current session; to ensure the format and location persists after a reboot, add the following line to your /etc/sysctl.conf configuration file:

   kernel.core_pattern=core.%p

3. Disable the AppArmor application (SUSE platforms), or Automatic Bug Reporting Tool (Red Hat platforms) that is preventing the generation of a core dump file:

   SUSE:

   rcapparmor stop

   Red Hat:

   chkconfig abrt off

4. Ensure that the core dump contains information resulting from processes that were granted permission via setuid and setgid:

   sysctl -w kernel.suid_dumpable=2

   Note: This permission override is only set for the current session; to ensure it persists after a reboot, add the following line to your /etc/sysctl.conf configuration file:

   kernel.suid_dumpable=2

5. Run the application for which you are expecting a core dump file.

   When the run time system receives an unhandled signal, a core dump file in created in the same directory as the application.