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


     ttyname, ttyname_r - return name of a terminal


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


     The  function  ttyname() returns a pointer to the null-terminated path-
     name 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.


     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.


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


     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                |


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


     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  tty-
     name_r()  on  the file descriptor in the new mount namespace will cause
     these functions to return NULL and set errno to ENODEV.


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


     This page is part of release 4.16 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 2017-05-03 TTYNAME(3)

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