ttyname

TTYNAME(3)                OpenBSD Programmer's Manual               TTYNAME(3)

NAME

     ttyname, ttyname_r, isatty, ttyslot - get name of associated terminal
     (tty) from file descriptor

SYNOPSIS

     #include <unistd.h>

     char *
     ttyname(int fd);

     int
     ttyname_r(int fd, char *name, size_t namesize);

     int
     isatty(int fd);

     int
     ttyslot(void);

DESCRIPTION

     These functions operate on the system file descriptors for terminal type
     devices.  These descriptors are not related to the standard I/O FILE
     typedef, but refer to the special device files found in /dev and named
     /dev/ttyXX and for which an entry exists in the initialization file
     /etc/ttys (see ttys(5)).

     The isatty() function determines if the file descriptor fd refers to a
     valid terminal type device.

     The ttyname() and ttyname_r() functions get the related device name of a
     file descriptor for which isatty() is true.  The ttyname_r() function
     stores the NUL-terminated pathname of the terminal associated with the
     file descriptor fd in the character array referenced by name.  The array
     is namesize characters long and should have space for the name and the
     terminating NUL character.  The maximum length of the terminal name is
     TTY_NAME_MAX.

     The ttyslot() function fetches the current process's control terminal
     number from the ttys(5) file entry.

RETURN VALUES

     The ttyname() function returns the NUL-terminated name if the device is
     found and isatty() is true; otherwise a null pointer is returned and
     errno is set to indicate the error.

     The ttyname_r() function returns zero if successful; otherwise an error
     number is returned.

     The isatty() function returns 1 if fd is associated with a terminal
     device; otherwise it returns 0 and errno is set to indicate the error.

     The ttyslot() function returns the unit number of the device file if
     found; otherwise the value zero is returned.

FILES

     /dev/*
     /etc/ttys

ERRORS

     The ttyname(), ttyname_r(), and isatty() functions will fail if:

     [EBADF]            The fd argument is not a valid file descriptor.

     [ENOTTY]           The fd argument does not refer to a terminal device.

     [ERANGE]           The value of namesize is smaller than the length of
                        the string to be returned including the terminating
                        NUL character.

SEE ALSO

     ioctl(2), ttys(5), dev_mkdb(8)

HISTORY

     The isatty(), ttyname(), and ttyslot() functions appeared in Version 7
     AT&T UNIX.  The ttyname_r() function appeared in the POSIX Threads
     Extension (1003.1c-1995).

BUGS

     The ttyname() function leaves its result in an internal static object and
     returns a pointer to that object.  Subsequent calls to ttyname() will
     modify the same object.

OpenBSD 5.1                      July 3, 2007                      OpenBSD 5.1