OPENPTY(3)                 Linux Programmer's Manual                OPENPTY(3)

       openpty, login_tty, forkpty - terminal utility functions

       #include <pty.h>

       int openpty(int *amaster, int *aslave, char *name,
                   const struct termios *termp,
                   const struct winsize *winp);

       pid_t forkpty(int *amaster, char *name,
                     const struct termios *termp,
                     const struct winsize *winp);

       #include <utmp.h>

       int login_tty(int fd);

       Link with -lutil.

       The  openpty()  function  finds an available pseudoterminal and returns
       file descriptors for the master and slave in amaster  and  aslave.   If
       name  is  not  NULL, the filename of the slave is returned in name.  If
       termp is not NULL, the terminal parameters of the slave will be set  to
       the values in termp.  If winp is not NULL, the window size of the slave
       will be set to the values in winp.

       The login_tty() function prepares for a login on the terminal fd (which
       may  be  a  real  terminal  device, or the slave of a pseudoterminal as
       returned by openpty()) by creating a new session, making  fd  the  con-
       trolling  terminal  for the calling process, setting fd to be the stan-
       dard input, output, and error streams of the current process, and clos-
       ing fd.

       The  forkpty() function combines openpty(), fork(2), and login_tty() to
       create a new process operating in a pseudoterminal.  The file  descrip-
       tor  of  the  master side of the pseudoterminal is returned in amaster,
       and the filename of the slave in name if it is not NULL.  The termp and
       winp arguments, if not NULL, will determine the terminal attributes and
       window size of the slave side of the pseudoterminal.

       If a call to openpty(), login_tty(), or forkpty() is not successful, -1
       is  returned  and  errno  is  set  to  indicate  the error.  Otherwise,
       openpty(), login_tty(), and the child process of  forkpty()  return  0,
       and the parent process of forkpty() returns the process ID of the child

       openpty() will fail if:

       ENOENT There are no available terminals.

       login_tty() will fail if ioctl(2) fails to set fd  to  the  controlling
       terminal of the calling process.

       forkpty() will fail if either openpty() or fork(2) fails.

       For   an   explanation   of   the  terms  used  in  this  section,  see

       |Interface            | Attribute     | Value                  |
       |forkpty(), openpty() | Thread safety | MT-Safe locale         |
       |login_tty()          | Thread safety | MT-Unsafe race:ttyname |

       These are BSD functions, present in glibc.  They are  not  standardized
       in POSIX.

       The  const  modifiers  were added to the structure pointer arguments of
       openpty() and forkpty() in glibc 2.8.

       In versions of glibc before 2.0.92, openpty() returns file  descriptors
       for a BSD pseudoterminal pair; since glibc 2.0.92, it first attempts to
       open a UNIX 98 pseudoterminal pair, and falls back  to  opening  a  BSD
       pseudoterminal pair if that fails.

       Nobody  knows  how much space should be reserved for name.  So, calling
       openpty() or forkpty() with non-NULL name may not be secure.

       fork(2), ttyname(3), pty(7)

       This page is part of release 4.04 of the Linux  man-pages  project.   A
       description  of  the project, information about reporting bugs, and the
       latest    version    of    this    page,    can     be     found     at

GNU                               2015-04-19                        OPENPTY(3)
Man Pages Copyright Respective Owners. Site Copyright (C) 1994 - 2021 Hurricane Electric. All Rights Reserved.