Preparing for a core dump

Note: This topic is only applicable to Linux-based platforms.

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.)

Note: The following commands must be run with root privileges.

Disable any size limitations that could stop the core dump file from being created in its entirety:
```
ulimit -c unlimited
```
Tip: To keep the size limits in place after a reboot, add the following for each appropriate <user>, to /etc/security/limits.conf:
```
<user>    soft    core    unlimited
<user>    hard    core    unlimited
```
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
```
Disable the AppArmor application (SUSE platforms), Automatic Bug Reporting Tool (Red Hat platforms), or Apport (Ubuntu platforms) that is preventing the generation of a core dump file:
SUSE:
```
rcapparmor stop
```
Red Hat:
```
chkconfig abrt off
```
Ubuntu:
```
systemctl stop apport.service 
systemctl disable apport.service
```
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
```

If required, configure the run-time environment, so that when the run-time system receives an unhandled signal, a core dump file in created in the same directory as the application; alternatively, if the application is set to programmatically invoke a core dump (CBL_CREATE_CORE), you can just run the application.