Provided by: manpages-posix-dev_2013a-2_all 
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 .