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TTYNAME(3)		 BSD Library Functions Manual		    TTYNAME(3)

NAME
     ttyname, ttyname_r, 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
     ttyname_r(int fd, char *buf, size_t len);

     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 ttyname() function returns the	name stored in a static	buffer which
     will be overwritten on subsequent calls.  The ttyname_r() function	takes
     a buffer and length as arguments to avoid this problem.

     The ttyslot() function fetches the	current	process' control terminal num-
     ber 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
     ttyname_r() function returns 0 if successful.  Otherwise an error number
     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

ERRORS
     The ttyname_r() may fail and return the following error codes:

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

     [ERANGE]		The bufsize argument is	smaller	than the length	of the
			string to be returned.

SEE ALSO
     ioctl(2), ttys(5)

HISTORY
     The isatty(), ttyname(), and ttyslot() functions appeared in Version 7
     AT&T UNIX.	 The ttyname_r() function appeared in FreeBSD 6.0.

BSD				 May 14, 2005				   BSD
NAME | LIBRARY | SYNOPSIS | DESCRIPTION | RETURN VALUES | FILES | ERRORS | SEE ALSO | HISTORY

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