Provided by: manpages-dev_4.04-2_all 

NAME
ttyname, ttyname_r - return name of a terminal
SYNOPSIS
#include <unistd.h>
char *ttyname(int fd);
int ttyname_r(int fd, char *buf, size_t buflen);
DESCRIPTION
The function ttyname() returns a pointer to the null-terminated pathname of the terminal device that is
open on the file descriptor fd, or NULL on error (for example, if fd is not connected to a terminal).
The return value may point to static data, possibly overwritten by the next call. The function
ttyname_r() stores this pathname in the buffer buf of length buflen.
RETURN VALUE
The function ttyname() returns a pointer to a pathname on success. On error, NULL is returned, and errno
is set appropriately. The function ttyname_r() returns 0 on success, and an error number upon error.
ERRORS
EBADF Bad file descriptor.
ENOTTY File descriptor does not refer to a terminal device.
ERANGE (ttyname_r()) buflen was too small to allow storing the pathname.
ATTRIBUTES
For an explanation of the terms used in this section, see attributes(7).
┌─────────────┬───────────────┬────────────────────────┐
│ Interface │ Attribute │ Value │
├─────────────┼───────────────┼────────────────────────┤
│ ttyname() │ Thread safety │ MT-Unsafe race:ttyname │
├─────────────┼───────────────┼────────────────────────┤
│ ttyname_r() │ Thread safety │ MT-Safe │
└─────────────┴───────────────┴────────────────────────┘
CONFORMING TO
POSIX.1-2001, POSIX.1-2008, 4.2BSD.
SEE ALSO
fstat(2), ctermid(3), isatty(3)
COLOPHON
This page is part of release 4.04 of the Linux man-pages project. A description of the project,
information about reporting bugs, and the latest version of this page, can be found at
http://www.kernel.org/doc/man-pages/.
Linux 2015-08-08 TTYNAME(3)