ttyname_r(3)

1TTYNAME(3)                 Linux Programmer's Manual                TTYNAME(3)
2
3
4

NAME

6       ttyname, ttyname_r - return name of a terminal
7

SYNOPSIS

9       #include <unistd.h>
10
11       char *ttyname(int fd);
12       int ttyname_r(int fd, char *buf, size_t buflen);
13

DESCRIPTION

15       The  function  ttyname() returns a pointer to the null-terminated path‐
16       name of the terminal device that is open on the file descriptor fd,  or
17       NULL on error (for example, if fd is not connected to a terminal).  The
18       return value may point to static data, possibly overwritten by the next
19       call.   The function ttyname_r() stores this pathname in the buffer buf
20       of length buflen.
21

RETURN VALUE

23       The function ttyname() returns a pointer to a pathname on success.   On
24       error,  NULL  is returned, and errno is set to indicate the error.  The
25       function ttyname_r() returns 0 on success, and an error number upon er‐
26       ror.
27

ERRORS

29       EBADF  Bad file descriptor.
30
31       ENODEV fd refers to a slave pseudoterminal device but the corresponding
32              pathname could not be found (see NOTES).
33
34       ENOTTY fd does not refer to a terminal device.
35
36       ERANGE (ttyname_r()) buflen was too small to allow  storing  the  path‐
37              name.
38

ATTRIBUTES

40       For  an  explanation  of  the  terms  used  in  this  section,  see at‐
41       tributes(7).
42
43       ┌─────────────────────────────┬───────────────┬────────────────────────┐
44       │Interface                    │ Attribute     │ Value                  │
45       ├─────────────────────────────┼───────────────┼────────────────────────┤
46       │ttyname()                    │ Thread safety │ MT-Unsafe race:ttyname │
47       ├─────────────────────────────┼───────────────┼────────────────────────┤
48       │ttyname_r()                  │ Thread safety │ MT-Safe                │
49       └─────────────────────────────┴───────────────┴────────────────────────┘
50

CONFORMING TO

52       POSIX.1-2001, POSIX.1-2008, 4.2BSD.
53

NOTES

55       A process that keeps a file descriptor that refers to a  pts(4)  device
56       open  when  switching  to another mount namespace that uses a different
57       /dev/ptmx instance may still accidentally find that a  device  path  of
58       the  same  name  for that file descriptor exists.  However, this device
59       path refers to a different device and thus can't be used to access  the
60       device  that  the file descriptor refers to.  Calling ttyname() or tty‐
61       name_r() on the file descriptor in the new mount namespace  will  cause
62       these functions to return NULL and set errno to ENODEV.
63

COLOPHON

68       This  page  is  part of release 5.13 of the Linux man-pages project.  A
69       description of the project, information about reporting bugs,  and  the
70       latest     version     of     this    page,    can    be    found    at
71       https://www.kernel.org/doc/man-pages/.
72
73
74
75Linux                             2021-03-22                        TTYNAME(3)