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 (con-
       sult the corresponding 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 associ-
       ated 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 character 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 char-
              acter.


       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  Technology -- Portable Operating System Interface (POSIX), The Open Group Base Specifications Issue 6, Copy-
       right (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.open-
       group.org/unix/online.html .



IEEE/The Open Group                                           2003                                                   TTYNAME(3P)