### 8.224 `SIGNAL` — Signal handling subroutine (or function)

Description:
  `SIGNAL(NUMBER, HANDLER [, STATUS])` causes external subroutine HANDLER to be executed with a single integer argument when signal NUMBER occurs. If HANDLER is an integer, it can be used to turn off handling of signal NUMBER or revert to its default action. See `signal(2)`.

  If `SIGNAL` is called as a subroutine and the STATUS argument is supplied, it is set to the value returned by `signal(2)`.

Standard:
  GNU extension
Class:
  Subroutine, function
Syntax:

  `CALL SIGNAL(NUMBER, HANDLER [, STATUS])`
  `STATUS = SIGNAL(NUMBER, HANDLER)`

Arguments:

  NUMBER | Shall be a scalar integer, with `INTENT(IN)`
  HANDLER | Signal handler (`INTEGER FUNCTION` or `SUBROUTINE`) or dummy/global `INTEGER` scalar. `INTEGER`. It is `INTENT(IN)`.
  STATUS | (Optional) STATUS shall be a scalar integer. It has `INTENT(OUT)`.

Return value:
  The `SIGNAL` function returns the value returned by `signal(2)`.
Example:

                program test_signal
                  intrinsic signal
                  external handler_print

                  call signal (12, handler_print)
                  call signal (10, 1)

                  call sleep (30)
                end program test_signal