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



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

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
       returned pointer and the string content might also be invalidated if
       the calling thread is terminated.

       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.1-2017, <unistd.h>

COPYRIGHT
       Portions of this text are reprinted and reproduced in electronic form
       from IEEE Std 1003.1-2017, Standard for Information Technology --
       Portable Operating System Interface (POSIX), The Open Group Base
       Specifications Issue 7, 2018 Edition, Copyright (C) 2018 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 .

       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 .



IEEE/The Open Group                  2017                           TTYNAME(3)
