--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/scripts/miscellaneous/popen2.m	Wed Apr 24 07:45:47 1996 +0000
@@ -0,0 +1,102 @@
+# Copyright (C) 1996 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 2, 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, write to the Free
+# Software Foundation, 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
+
+function [in, out, pid] = popen2 (command, args)
+
+# usage: [IN, OUT, PID] = popen2 (COMMAND, ARGS)
+#
+# Start a subprocess with two-way communication.  COMMAND specifies
+# the name of the command to start.  ARGS is an array of strings
+# containing options for COMMAND.  IN and out are the file ids of the
+# input and streams for the subprocess, and PID is the process id of
+# the subprocess, or -1 if COMMAND could not be executed.
+#
+# Example:
+#
+#  [in, out, pid] = popen2 ("sort", "-nr");
+#  fputs (in, "these\n");
+#  fputs (in, "are\n");
+#  fputs (in, "some\n");
+#  fputs (in, "strings\n");
+#  fclose (in);
+#  while (isstr (s = fgets (out)))
+#    fputs (stdout, s);
+#  endwhile
+#  fclose (out);
+
+  in = -1;
+  out = -1;
+  pid = -1;
+
+  if (nargin == 1 || nargin == 2)
+
+    if (nargin == 1)
+      args = "";
+    endif
+
+    if (isstr (command))
+
+      [stdin_pipe, stdin_status] = pipe ();
+      [stdout_pipe, stdout_status] = pipe ();
+
+      if (stdin_status == 0 && stdout_status == 0)
+
+	pid = fork ();
+
+	if (pid == 0) 
+
+	  fclose (stdin_pipe (2));
+	  fclose (stdout_pipe (1));
+
+	  dup2 (stdin_pipe (1), stdin);
+	  fclose (stdin_pipe (1));
+
+	  dup2 (stdout_pipe (2), stdout);
+	  fclose (stdout_pipe (2));
+
+	  if (exec (command, args) < 0)
+	    error ("popen2: unable to start process `%s'", command);
+	    exit (0);
+	  endif
+
+	elseif (pid)
+
+	  fclose (stdin_pipe (1));
+	  fclose (stdout_pipe (2));
+
+	  if (fcntl (stdout_pipe (1), __F_SETFL__, __O_NONBLOCK__) < 0)
+	    error ("popen2: error setting file mode");
+	  else
+	    in = stdin_pipe (2);
+	    out = stdout_pipe (1);
+	  endif
+
+	elseif (pid < 0) 
+	  error ("popen2: fork failed -- unable to create child process");
+	endif
+      else
+	error ("popen2: pipe creation failed");
+      endif
+    else
+      error ("popen2: file name must be a string");
+    endif
+  else
+    usage ("[in, out, pid] = popen2 (command, args)");
+  endif
+
+endfunction