## Copyright (C) 2004-2015 John W. Eaton
##
## This file is part of Octave.
##
## Octave is free software; you can redistribute it and/or modify it
## under the terms of the GNU General Public License as published by
## the Free Software Foundation; either version 3 of the License, or (at
## your option) any later version.
##
## Octave is distributed in the hope that it will be useful, but
## WITHOUT ANY WARRANTY; without even the implied warranty of
## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
## General Public License for more details.
##
## You should have received a copy of the GNU General Public License
## along with Octave; see the file COPYING.  If not, see
## <http://www.gnu.org/licenses/>.

## -*- texinfo -*-
## @deftypefn  {Function File} {} unix ("@var{command}")
## @deftypefnx {Function File} {@var{status} =} unix ("@var{command}")
## @deftypefnx {Function File} {[@var{status}, @var{text}] =} unix ("@var{command}")
## @deftypefnx {Function File} {[@dots{}] =} unix ("@var{command}", "-echo")
## Execute a system command if running under a Unix-like operating system,
## otherwise do nothing.
##
## Octave waits for the external command to finish before returning the exit
## status of the program in @var{status} and any output in @var{text}.
##
## When called with no output argument, or the @qcode{"-echo"} argument is
## given, then @var{text} is also sent to standard output.
## @seealso{dos, system, isunix, ismac, ispc}
## @end deftypefn

## Author: octave-forge ???
## Adapted by: jwe

function [status, text] = unix (command, echo_arg)

  if (nargin < 1 || nargin > 2)
    print_usage ();
  elseif (isunix ())
    [status, text] = system (command);
    if (nargin > 1 || nargout == 0)
      printf ("%s\n", text);
    endif
  endif

endfunction


%!test
%! cmd = ls_command ();
%! warning ("off", "Octave:undefined-return-values", "local");
%! [status, output] = unix (cmd);
%!
%! if (isunix ())
%!   assert (status, 0);
%!   assert (ischar (output));
%!   assert (! isempty (output));
%! else
%!   assert (status, []);
%!   assert (output, []);
%! endif

%!error unix ()
%!error unix (1, 2, 3)