1TTYNAME(3)                 Linux Programmer's Manual                TTYNAME(3)
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NAME

6       ttyname, ttyname_r - return name of a terminal
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SYNOPSIS

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

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

24       The function ttyname() returns a pointer to a pathname on success.   On
25       error,  NULL is returned, and errno is set appropriately.  The function
26       ttyname_r() returns 0 on success, and an error number upon error.
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ERRORS

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

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

CONFORMING TO

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

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

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

67       This page is part of release 5.07 of the Linux  man-pages  project.   A
68       description  of  the project, information about reporting bugs, and the
69       latest    version    of    this    page,    can     be     found     at
70       https://www.kernel.org/doc/man-pages/.
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74Linux                             2019-10-10                        TTYNAME(3)
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