Troubles using open-pipe

I am opening a pipe between my lisp app and a shell program. The program 
reads from stdin and prints to stdout. The problem is that the program 
doesn't print until the stdin stream is closed, and I can't figure out a 
way to close the pipe (a bidirectional-stream of sorts) in only one 
direction.  My code is

#| ignore typos |#
(setf stream (sys:open-pipe *my-app-path* :direction :io))
(write-line "some stuff" stream)
(write-line "some more stuff" stream)
;; this is where I would need to close the ouput-stream
(write-char #\eot stream) ;;my attempt
(read-line stream)

One thing I had tried was to manually (write-char #\eot stream) which (i 
believe) puts an end-of-file character into the stream, but that *seems* 
to be caught by lispworks which closes off the stream completely and 
allows no more reading or writing...  strangely enough, however... if I 
set the program to redirect output to a file, and still try the 
(write-char #\eot stream), nothing is ever printed to the file.  It does 
work if I redirect to file and run (close stream) instead, but then I 
can no longer read from the stream, so that is not a good enough solution.

Thanks!

Andrew

Re: Troubles using open-pipe

Andrew Shilliday wrote:
> I am opening a pipe between my lisp app and a shell program. The program 
> reads from stdin and prints to stdout. The problem is that the program 
> doesn't print until the stdin stream is closed, and I can't figure out a 
> way to close the pipe (a bidirectional-stream of sorts) in only one 
> direction.  My code is
> 
> #| ignore typos |#
> (setf stream (sys:open-pipe *my-app-path* :direction :io))
> (write-line "some stuff" stream)
> (write-line "some more stuff" stream)
> ;; this is where I would need to close the ouput-stream
> (write-char #\eot stream) ;;my attempt
> (read-line stream)
> 

do

(force-output stream)
or

(finish-output stream)

see

http://www.lispworks.com/reference/HyperSpec/Body/f_finish.htm

Closing the stream will force the output to be sent and thus has the
same affect.

Wade

Re: Troubles using open-pipe

On Jul 20, 2004, at 6:38 PM, Andrew Shilliday wrote:

> I am opening a pipe between my lisp app and a shell program. The 
> program reads from stdin and prints to stdout. The problem is that the 
> program doesn't print until the stdin stream is closed, and I can't 
> figure out a way to close the pipe (a bidirectional-stream of sorts) 
> in only one direction.  My code is

I don't know if this is related or not, but I reported a bug in January 
where I/O with open-pipe on OS X seems to hang indefinitely until you 
click the mouse on any window. Below is a test program that illustrates 
this issue. I just tested with 4.3.7 on a dual 1.8 G5 running OS X 
10.3.4. It stops after about 300 lines until I click the mouse on the 
listener window. Last time I tested, it would never hang on my G4 
PowerBook.

Best,

John DeSoi, Ph.D.

(defun test (&optional (lines 1000))
   (let ((s (system:open-pipe "/bin/csh" :direction :io :buffered t))
         (in (with-output-to-string (input)
               (loop for i from 1 to lines do
                     (write-line (format nil "echo '~d 0123456789 
01234567890 0123456789 0123456789'" i) input)))))
     (with-input-from-string (input in)
       (loop for line = (read-line input nil nil)
             while line do
             (write-line line s)
             (finish-output s)
             (princ (read-as-string s)))
       (close s)
       (values))))