PROLOG

       This  manual  page  is part of the POSIX Programmer's Manual.  The Linux implementation of
       this interface may differ (consult 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 associated with file descriptor fildes.   The  application  shall
       not  modify  the  string returned. The returned pointer might be invalidated or the string
       content might be overwritten by a subsequent call to ttyname().

       The ttyname() function need not 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 file associated with the fildes argument is not a terminal.

       The ttyname_r() function may fail if:

       EBADF  The fildes argument is not a valid file descriptor.

       ENOTTY The file associated with the fildes argument is not 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 POSIX.1‐2008, <unistd.h>

COPYRIGHT

       Portions  of  this  text  are  reprinted  and  reproduced in electronic form from IEEE Std
       1003.1, 2013 Edition, Standard for Information Technology  --  Portable  Operating  System
       Interface  (POSIX),  The Open Group Base Specifications Issue 7, Copyright (C) 2013 by the
       Institute of Electrical and Electronics Engineers, Inc  and  The  Open  Group.   (This  is
       POSIX.1-2008  with  the  2013  Technical  Corrigendum  1  applied.)  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.unix.org/online.html .

       Any typographical or formatting errors that appear in this page are most  likely  to  have
       been  introduced  during  the conversion of the source files to man page format. To report
       such errors, see https://www.kernel.org/doc/man-pages/reporting_bugs.html .