7.20.4.3 The exit function
Synopsis
       #include <stdlib.h>
       void exit(int status);
Description
The exit function causes normal program termination to occur. If more than one call to
the exit function is executed by a program, the behavior is undefined.

First, all functions registered by the atexit function are called, in the reverse order of
their registration,253) except that a function is called after any previously registered
functions that had already been called at the time it was registered. If, during the call to
any such function, a call to the longjmp function is made that would terminate the call
to the registered function, the behavior is undefined.

Next, all open streams with unwritten buffered data are flushed, all open streams are
closed, and all files created by the tmpfile function are removed.

Finally, control is returned to the host environment. If the value of status is zero or
EXIT_SUCCESS, an implementation-defined form of the status successful termination is
returned. If the value of status is EXIT_FAILURE, an implementation-defined form
of the status unsuccessful termination is returned. Otherwise the status returned is
implementation-defined.

Returns
The exit function cannot return to its caller.