nullptr [enable | disable]
When null-pointer dereferences are enabled, any user program attempt to read memory in the first page (addresses 0-4095) will successfully return zero. When disabled, these memory reads behave like any other bad memory reference and cause a SIGSEGV signal to be sent to the referencing lightweight process. Memory writes to page 0 always generate SIGSEGV.
The default behavior can be changed by changing the NULLPTR tunable parameter.
The nullptr command can be used to override the default behavior for a particular user, based on the user ID of the invoking process.
The nullptr command can be called with the following arguments:
With no arguments, nullptr displays the behavior in effect for the current user.