Re: How to run shell command with stream input, to get string output

[Noam Postavsky <npostavs@gmail.com>]

On Mon, 1 Jul 2019 at 05:45, Jean Louis <bugs@gnu.support> wrote:

> Something like that, but it does not work as
> output of process is not written in the buffer.

When input is not newline terminated, cat requires two EOFs. I find
this is the case when running outside of Emacs as well.

(with-temp-buffer
  (let* ((process (start-process "NEW" (current-buffer) "cat")))
    ;; Don't include "Process NEW finished\n".
    (set-process-sentinel process #'ignore)
    (process-send-string process "Hello")
    (process-send-eof process)
    (process-send-eof process)
    (while (accept-process-output process))
    (buffer-string)))

But if you don't need asynchoronous input, call-process-region is simpler:

(with-temp-buffer
  (insert "Hello")
  (call-process-region (point-min) (point-max)
               "tr" t '(t t) nil "a-z" "A-Z")
  (buffer-string))