ttyname(3) — Linux manual page


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

NAME         top

       ttyname, ttyname_r - return name of a terminal

SYNOPSIS         top

       #include <unistd.h>

       char *ttyname(int fd);

       int ttyname_r(int fd, char *buf, size_t buflen);

DESCRIPTION         top

       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         top

       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

ERRORS         top

       EBADF  Bad file descriptor.

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

       ENOTTY fd does not refer to a terminal device.

       ERANGE (ttyname_r()) buflen was too small to allow storing the

ATTRIBUTES         top

       For an explanation of the terms used in this section, see

       │Interface   Attribute     Value                  │
       │ttyname()   │ Thread safety │ MT-Unsafe race:ttyname │
       │ttyname_r() │ Thread safety │ MT-Safe                │

CONFORMING TO         top

       POSIX.1-2001, POSIX.1-2008, 4.2BSD.

NOTES         top

       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         top

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

COLOPHON         top

       This page is part of release 5.08 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

Linux                            2019-10-10                       TTYNAME(3)

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