If you change the "process*" call in the below program to run your
command, and run this program in DrRacket with "View -> Show Log",
hopefully you see the output from your command promptly.
#lang racket/base
(require racket/system)
(apply (lambda (stdout-in
stdin-out
pid
stderr-in
process-proc)
(let* ((buf-size 4096)
(buf-bytes (make-bytes buf-size)))
(let loop ()
(let ((evt (sync/enable-break stdout-in stderr-in)))
;; ...
(let ((read-result (read-bytes-avail! buf-bytes evt)))
(cond ((eof-object? read-result)
(log-error "EOF!")
;; ...
(void))
;; ...
(else
(log-error "OUTPUT: ~S" (subbytes buf-bytes 0
read-result))
(loop))))))
;; ...
(close-output-port stdin-out)
(close-input-port stdout-in)
(close-input-port stderr-in)))
(process* "/bin/sh"
"-c"
"while true ; do echo -n abc ; sleep 3 ; done"))
(I wrote the code this particular way, using a bytes buffer, because
it's a good starting point for doing fancier things, such as if you're
trying to recognize particular output and handle it specially, or if
you're interacting with the process. This is as far as I can help,
though. Depending on the entirety of what you want to do with the
output, getting this right can easily take hours and end up looking like
systems programming. Or you can look at doing it with first-class
continuations, which should be more elegant, but continuations hurt
people's brains initially, and i'm not sure how performance would compare.)
Neil V.
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