Question

In Mac 10.8.2, use gfortran 4.7.2 to compile the following code:

program test
    write(*, *) isatty(6)
end program test

The program just not response and not return. Any idea?

Answer 1

I’m not really sure why you get no output, it works fine for me with gfortran 4.7.2 on Linux. You could try whether writing your own interface to C’s isatty makes any difference:

program test
  implicit none

  interface
    function my_isatty(fd) bind(C, name = 'isatty')
      use, intrinsic :: iso_c_binding, only: c_int
      integer(c_int)        :: my_isatty
      integer(c_int), value :: fd
    end function
  end interface

  ! Standard output should be at 1 in C:
  print*, my_isatty(1) 
end program test

I get the following output:

$ ./a.out
    1
$ ./a.out > b && cat b
    0