ttyname3
Return name of a terminal
Usage
#include <unistd.h>
char *ttyname(int fd); int ttyname_r(size_t size; int fd, char buf[size], size_t size);
Library
Standard C library (libc, -lc)
Overview
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 size size.
Return value
The function ttyname() returns a pointer to a pathname on success. On error, NULL is returned, and errno is set to indicate the error. The function ttyname_r() returns 0 on success, and an error number upon error.
Errors
- 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()) size was too small to allow storing the pathname.
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 |
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.
Releases
19 releases since Debian 1.1 (Buzz); the text changed 15 times.