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OPENPTY(3)                 Library Functions Manual                 OPENPTY(3)

     openpty, login_tty, forkpty -- tty utility functions

     System Utilities Library (libutil, -lutil)

     #include <&lt;util.h>&gt;

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

     login_tty(int fd);

     forkpty(int *amaster, char *name, struct termios *termp, struct winsize

     The openpty(), login_tty(), and forkpty() functions perform manipulations
     on ttys and pseudo-ttys.

     The openpty() function finds an available pseudo-tty and returns file
     descriptors for the master and slave in amaster and aslave.  If name is
     non-null, the filename of the slave is returned in name.  If termp is
     non-null, the terminal parameters of the slave will be set to the values
     in termp.  If winp is non-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
     current 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 (to the parent process
     only) in amaster.  The filename of the slave is returned (to both the
     parent and child processes) in name if name is non-null.  The termp and
     winp parameters, if non-null, will determine the terminal attributes and
     window size of the slave side of the pseudo-tty.

     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 ttys.

     [EPERM]            The caller was not the superuser and the ptm(4) device
                        is missing or not configured.

     login_tty() 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.


NetBSD 6.1.5                   November 28, 2008                  NetBSD 6.1.5