Descendents of class Exception are used to communicate between raise methods and rescue statements in begin/end blocks. Exception objects carry information about the exception—its type (the exception’s class name), an optional descriptive string, and optional traceback information. Programs may subclass Exception to add additional information.

Methods
N
S
Class Public methods
SystemExit.new(status=0) => system_exit

Create a new SystemExit exception with the given status.

Source: show 

static VALUE
exit_initialize(argc, argv, exc)
    int argc;
    VALUE *argv;
    VALUE exc;
{
    VALUE status = INT2FIX(EXIT_SUCCESS);
    if (argc > 0 && FIXNUM_P(argv[0])) {
        status = *argv++;
        --argc;
    }
    rb_call_super(argc, argv);
    rb_iv_set(exc, "status", status);
    return exc;
}
Instance Public methods
system_exit.status => fixnum

Return the status value associated with this system exit.

Source: show 

static VALUE
exit_status(exc)
    VALUE exc;
{
    return rb_attr_get(exc, rb_intern("status"));
}
system_exit.success? => true or false

Returns true if exiting successful, false if not.

Source: show 

static VALUE
exit_success_p(exc)
    VALUE exc;
{
    VALUE status = rb_attr_get(exc, rb_intern("status"));
    if (NIL_P(status)) return Qtrue;
    if (status == INT2FIX(EXIT_SUCCESS)) return Qtrue;
    return Qfalse;
}