NAME    [Toc]    [Back]

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

LIBRARY    [Toc]    [Back]

     Standard C Library (libc, -lc)

SYNOPSIS    [Toc]    [Back]

     #include <unistd.h>

     char *
     ttyname(int fd);

     int
     isatty(int fd);

     #include <stdlib.h>

     int
     ttyslot();

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() 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    [Toc]    [Back]

     The ttyname() function returns 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.

SEE ALSO    [Toc]    [Back]

     ioctl(2), ttys(5)

STANDARDS    [Toc]    [Back]

     The ttyname() and isatty() functions conform to ISO/IEC 9945-1:1990
     (``POSIX.1'').

HISTORY    [Toc]    [Back]

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

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.

BSD                              June 4, 1993                              BSD