TTYNAME(3P)						     POSIX Programmer's Manual						       TTYNAME(3P)

PROLOG

       This  manual page is part of the POSIX Programmer's Manual.  The Linux implementation of this interface may differ (consult the correspond-
       ing Linux manual page for details of Linux behavior), or the interface may not be implemented on Linux.

NAME

       ttyname, ttyname_r - find the pathname of a terminal

SYNOPSIS

       #include <unistd.h>

       char *ttyname(int fildes);

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

DESCRIPTION

       The ttyname() function shall return a pointer to a string containing a null-terminated  pathname  of  the  terminal  associated	with  file
       descriptor fildes. The return value may point to static data whose content is overwritten by each call.

       The ttyname() function need not be reentrant. A function that is not required to be reentrant is not required to be thread-safe.

       The ttyname_r() function shall store the null-terminated pathname of the terminal associated with the file descriptor fildes in the charac-
       ter array referenced by name. The array is namesize characters long and should have space for the name and the terminating null	character.
       The maximum length of the terminal name shall be {TTY_NAME_MAX}.

RETURN VALUE

       Upon  successful  completion,  ttyname()  shall	return a pointer to a string. Otherwise, a null pointer shall be returned and errno set to
       indicate the error.

       If successful, the ttyname_r() function shall return zero. Otherwise, an error number shall be returned to indicate the error.

ERRORS

       The ttyname() function may fail if:

       EBADF  The fildes argument is not a valid file descriptor.

       ENOTTY The fildes argument does not refer to a terminal.

       The ttyname_r() function may fail if:

       EBADF  The fildes argument is not a valid file descriptor.

       ENOTTY The fildes argument does not refer to a terminal.

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

       The following sections are informative.

EXAMPLES

       None.

APPLICATION USAGE

       None.

RATIONALE

       The term ``terminal'' is used instead of the historical term ``terminal device'' in order to avoid a reference to an undefined term.

       The thread-safe version places the terminal name in a user-supplied buffer and returns a non-zero value if it  fails.  The  non-thread-safe
       version may return the name in a static data area that may be overwritten by each call.

FUTURE DIRECTIONS

       None.

SEE ALSO

       The Base Definitions volume of IEEE Std 1003.1-2001, <unistd.h>

COPYRIGHT

       Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1, 2003 Edition, Standard for Information Technol-
       ogy -- Portable Operating System Interface (POSIX), The Open Group Base Specifications Issue 6, Copyright (C) 2001-2003 by the Institute of
       Electrical  and	Electronics  Engineers, Inc and The Open Group. In the event of any discrepancy between this version and the original IEEE
       and The Open Group Standard, the original IEEE and The Open Group Standard is the referee document. The original Standard can  be  obtained
       online at http://www.opengroup.org/unix/online.html .

IEEE
/The Open Group						       2003							       TTYNAME(3P)