On Thu, Jan 09, 2003 at 2:21 PM, Jan Hudec wrote: > On Thu, Jan 09, 2003 at 02:13:42PM -0800, Ed Vance wrote: > > On Thu, Jan 09, 2003 at 12:42 PM, Jan Hudec wrote: > > > > > > On Thu, Jan 09, 2003 at 12:29:45PM -0800, Ed Vance wrote: > > > > Hi Jan, > > > > > > > > IIRC, a process must first have no controlling tty to get a > > > > new one assigned on the next open of a tty. Controlling tty > > > > assignments are sticky and are unaffected by closing. Once > > > > assigned, the assignment persists even if the process > > > > closes or redirects all streams open to that tty. For > > > > [ ... ] > > > > > > > > I hope I got that right ... > > > > > > Thanks, this should help. The trick is, that I have a program > > > that correctly claims controling tty, but I want to redirect > > > it to a different tty. And a terminal can not be a controling > > > terminal of more than one session. So I need something, that > > > will keep the pty (terminal emulator) open, but not a > > > controling terminal of anything. > > > > Do you mean something like the following sequence? > > > > process A has serial port as CTTY. > > process A opens a master pseudo terminal. > > process A forks child process B. > > process B ioctl TIOCNOTTY serial port to remove B's CTTY > > assignment. > > process B closes serial port streams. > > process B opens corresponding slave pseudo terminal, > > becomes B's CTTY. > > I think, that it's a bit different. It should look like following: > process A has pty/1 as ctty. > process A makes pty/1 available (presumably via TIOCNOTTY) > process B has no ctty (there is something about setsid I don't fully > understand) > process A tells process B that it can use pty/1 > process B opens pty/1 and makes it it's controling terminal > (TIOCSCTTY) > > The reason behind this: I have a process that logs a LOT to > stdout/stderr, does "setterm" ioctls on it and needs WINCH > signal (thus a controling tty). I want to run it from gdb > and have gdb and this programs output separated. Thus I use > gdb's tty command. But I need to make a tty available (under > X, that is in some terminal emulator). > If B calls setsid() successfully, then B opening pty/1 should make pty/1 ctty of B. Should not need to use TIOCSCTTY ioctl unless pty/1 still has a session attached, which it will if process A was not the session leader. Then you would not need the TIOCNOTTY and would need to use TIOCSCTTY with arg=1 to wrestle pty/1 away from its current group. Which call is returning an error? ---------------------------------------------------------------- Ed Vance edv (at) macrolink (dot) com Macrolink, Inc. 1500 N. Kellogg Dr Anaheim, CA 92807 ---------------------------------------------------------------- -- Kernelnewbies: Help each other learn about the Linux kernel. Archive: http://mail.nl.linux.org/kernelnewbies/ FAQ: http://kernelnewbies.org/faq/
