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 example, a > process still receives signals generated the keyboard of its controlling > tty, even if all streams have been redirected. By default, a child process > inherits the parent's controlling tty assignment. So, the child process must > use the TIOCNOTTY ioctl on its controlling tty to remove the controlling tty > assignment. It does not matter that a stream is already open to the previous > controlling tty. Then, the next open of a tty will assign that tty as the > new controlling tty, unless it is opened with the O_NOCTTY flag or the tty > is already the controlling tty of another process, which it will be if there > was a getty on it. > > 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. > -----Original Message----- > From: Jan Hudec [mailto:bulb@ucw.cz] > Sent: Thursday, January 09, 2003 11:33 AM > To: kernelnewbies@nl.linux.org > Subject: Re: Making terminal available for TIOCSCTTY > > > On Wed, Jan 08, 2003 at 01:50:45PM -0800, Seth Arnold wrote: > > On Tue, Jan 07, 2003 at 01:26:24PM +0100, Jan Hudec wrote: > > > Is it somehow possible to obtain a pty (not interested in usused virtual > > > console - only in different kinds of teminal emulators) so that > > > a process that has it's stdin, stdout and stderr redirected there can > > > claim it it's controling tty? > > > > Between the ioctl TIOCNOTTY and opening new terminal devices without > > using O_NOCTTY should re-associate your process with a new terminal. > > (Check open(2) for more hints.) > > I know how to make a pty my controling terminal. I however don't know > how to make a pty suitable for using as controling tty for a process, > whose parent has completely different controling tty. > > ---------------------------------------------------------------------------- > --- > Jan 'Bulb' Hudec > <bulb@ucw.cz> > -- > Kernelnewbies: Help each other learn about the Linux kernel. > Archive: http://mail.nl.linux.org/kernelnewbies/ > FAQ: http://kernelnewbies.org/faq/ > ------------------------------------------------------------------------------- Jan 'Bulb' Hudec <bulb@ucw.cz> -- Kernelnewbies: Help each other learn about the Linux kernel. Archive: http://mail.nl.linux.org/kernelnewbies/ FAQ: http://kernelnewbies.org/faq/
