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



NAME
       openpty, login_tty, forkpty - tty utility functions

SYNOPSIS
       #include <pty.h>  /* for openpty and forkpty */
       #include <utmp.h> /* for login_tty */

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

       int login_tty(int fd);

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

DESCRIPTION
       The  openpty()  function finds an available pseudo-tty and
       returns file descriptors for the master and slave in amas-
       ter  and aslave.  If name is not NULL, the filename of the
       slave is returned in name.  If termp is not NULL, the ter-
       minal 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 tty
       fd (which may be a real tty device,  or  the  slave  of  a
       pseudo-tty  as  returned  by  openpty()) by creating a new
       session, making fd the controlling terminal for  the  cur-
       rent process, setting fd to be the standard input, output,
       and error streams of the current process, and closing  fd.

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

RETURN VALUES
       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 pro-
       cess of forkpty() returns the process ID of the child pro-
       cess.

ERRORS
       openpty() will fail if:

       ENOENT There are no available ttys.

       login_pty()  will  fail  if ioctl() fails to set fd to the
       controlling terminal of the current process.

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

NOTE
       The login_tty() function is  included  in  libutil,  hence
       you'll  need  to  add ``-lutil'' to your compiler command-
       line.

FILES
       /dev/[pt]ty[pqrstuwxyzabcdePQRST][0123456789abcdef]

CONFORMING TO
       These are BSD functions, present in libc5 and glibc2.

SEE ALSO
       fork(k)



BSD MANPAGE                 2001-12-13                 OPENPTY(Y)