OPENPTY

NAME
     openpty, login_tty, forkpty -- tty utility functions

SYNOPSIS
     #include <util.h>

     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(), 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
     creates 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 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.

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 process of forkpty() returns the process ID of the child
     process.

ERRORS
     openpty() will fail if:

     [ENOENT]           There are no available ttys.

     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.

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

SEE ALSO
     fork(2)

BUGS
     The names of the virtual consoles for the i386 PCVT console driver conflict
     with what would be the seventh group of pseudo-ttys, so openpty()
     skips /dev/[pt]tyv[0123456789abcdef] while looking for pseudo-ttys.

BSD                            November 4, 1996                            BSD