NAME    [Toc]    [Back]

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

SYNOPSIS    [Toc]    [Back]

     #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    [Toc]    [Back]

     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 null-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    [Toc]    [Back]

     The ttyname() and ttyname_r() functions return the null-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  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    [Toc]    [Back]

     /dev/*
     /etc/ttys

ERRORS    [Toc]    [Back]

     The ttyname() 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    [Toc]    [Back]

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

HISTORY    [Toc]    [Back]

     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    [Toc]    [Back]

     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      3.6                           June      4,      1993