Re: start emacs without creating frames and connect with emacsclient later

[Johannes Weiner <hannes@saeurebad.de>]

Hi,

Dan Nicolaescu <dann@ics.uci.edu> writes:

> It seemed that this TODO item shouldn't be that hard to do given that we
> have all the infrastructure:
>
> ** Make "emacs --daemon" start emacs without showing any frame. 
> Use emacsclient later to open frames.
>
>
> 10 minutes later it turned out to be true.
>
> The patch below implements it.
>
> emacs -daemon &

Uhm, hardly a daemon if it quits when I quit the shell.

> will start emacs without creating any frames, and it starts the server.
>
> Later you can do:
>
> emacsclient -t FILENAME
>
> will create a tty frame.
>
> and
> emacsclient -c FILENAME
>
> will create an X11 frame.
>
> Not sure what to do about:
> emacsclient FILENAME
>
> it won't do anything visibe if no other frame is available.  Should it
> create one?

I think a good solution would be to do it like emacs itself does it:
Start a graphical frame (unless -nw) when that is possible, otherwise a
terminal frame.

Right now I use the below program as a workaround, perhaps someone might
find it interesting.

	Hannes

#define _XOPEN_SOURCE
#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <fcntl.h>
#include <unistd.h>

static const char emacs[]	= "emacs";
static char *args[]		= { "emacs", "-f", "server-start", NULL };

/* Run the emacs server */
void child_emacs(char *slavename)
{
	int slave;

	setsid();
	slave = open(slavename, O_RDWR);
	dup2(slave, 0);
	dup2(slave, 1);
	dup2(slave, 2);
	execvp(emacs, args);
	abort();
}

/* Run the reader that unblocks emacs' terminal */
void child_reader(int master)
{
	char buf[512];

	setsid();

	/* could be used for debugging in the future */
	while (read(master, buf, sizeof(buf)))
		/* do nothing */;
}

int main(void)
{
	int master;
	char *slavename;

	/* Open master terminal */
	master = open("/dev/ptmx", O_RDWR);
	grantpt(master);
	unlockpt(master);
	slavename = ptsname(master);

	/* Fork the emacs process */
	switch (fork()) {
	case -1:
		abort();
		break;
	case 0:
		child_emacs(slavename);
		break;
	default:
		/* Fork the reader process */
		switch (fork()) {
		case -1:
			abort();
			break;
		case 0:
			child_reader(master);
			break;
		}
	}

	return 0;
}