ttyname

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



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.

       ENODEV File descriptor refers to a slave pseudoterminal device but the
              corresponding pathname could not be found (see NOTES).

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.

NOTES
       A process that keeps a file descriptor that refers to a pts(4) device
       open when switching to another mount namespace that uses a different
       /dev/ptmx instance may still accidentally find that a device path of
       the same name for that file descriptor exists.  However, this device
       path refers to a different device and thus can't be used to access the
       device that the file descriptor refers to.  Calling ttyname() or
       ttyname_r() on the file descriptor in the new mount namespace will
       cause these functions to return NULL and set errno to ENODEV.

SEE ALSO
       tty(1), fstat(2), ctermid(3), isatty(3), pts(4)

COLOPHON
       This page is part of release 5.02 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
       https://www.kernel.org/doc/man-pages/.



Linux                             2017-05-03                        TTYNAME(3)