login_tty(3) - NetBSD Manual Pages

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OPENPTY(3)              NetBSD Library Functions Manual             OPENPTY(3)


NAME

     openpty, login_tty, forkpty -- tty utility functions


LIBRARY

     System Utilities Library (libutil, -lutil)


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.  The length of
     name is limited to PATH_MAX as any other regular path name, so a buffer
     of this size should be used.  If termp is non-null, the terminal parame-
     ters 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.


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.


FILES

     /dev/[pt]ty[p-zP-T][0-9a-zA-Z]


ERRORS

     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 ter-
     minal of the current process.  forkpty() will fail if either openpty() or
     fork() fails.


SEE ALSO

     fork(2)

NetBSD 8.0                       July 27, 2012                      NetBSD 8.0