TTYNAME

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

LIBRARY
     Standard C Library (libc, -lc)

SYNOPSIS
     #include <unistd.h>

     char *
     ttyname(int fd);

     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() function gets the related device name of a file descriptor
     for which isatty() is true

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

RETURN VALUES
     The ttyname() function returns the null terminated name if the device is
     found and isatty() is true; otherwise a NULL pointer is returned.

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

FILES
     /dev/*
     /etc/ttys

SEE ALSO
     ioctl(2), ttys(5)

HISTORY
     A isatty(), ttyname(), and ttyslot() function appeared in Version 7 AT&T
     UNIX.

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.

BSD                              June 4, 1993                              BSD