Re: Confused about sending text to a subprocess

[Sean McAfee <eefacm@gmail.com>]

Harald Hanche-Olsen <hanche@math.ntnu.no> writes:
> + Sean McAfee <eefacm@gmail.com>:
>> So I have this little Perl script:
>> [...]
>> I invoke it from Emacs like this:
>>
>>   (let ((proc (start-process "x" nil "/path/to/perl/script")))
>>     (process-send-string proc "foo\n")
>>     (process-send-eof proc))
>>
>> It works as I expect.  But if I leave off that newline:
>>
>>     (process-send-string proc "foo")
>>
>> ...then the subprocess does not exit.
>
> That is because emacs runs it in a pty, and "eof" on a pty in line
> buffered mode is signaled to the reading process by read() returning 0
> bytes.

Ah, OK, that makes sense.  I was expecting an ordinary pipe.  And a
little more digging in the manual turned up the variable
process-connection-type, which if nil will cause the processes started
by start-process to be connected with an ordinary pipe.

Thanks for the tip!