TTYNAME(3) OpenBSD Programmer's Manual TTYNAME(3)
ttyname, ttyname_r, isatty, ttyslot - get name of associated terminal
(tty) from file descriptor
ttyname_r(int fd, char *name, size_t namesize);
These functions operate on the system file descriptors for terminal type
devices. These descriptors are not related to the standard I/O FILE
typedef, but refer to the special device files found in /dev and named
/dev/ttyXX and for which an entry exists in the initialization file
/etc/ttys (see ttys(5)).
The isatty() function determines if the file descriptor fd refers to a
valid terminal type device.
The ttyname() and ttyname_r() functions get the related device name of a
file descriptor for which isatty() is true. The ttyname_r() function
stores the NUL-terminated pathname of the terminal associated with the
file descriptor fd in the character array referenced by name. The array
is namesize characters long and should have space for the name and the
terminating NUL character. The maximum length of the terminal name is
The ttyslot() function fetches the current process's control terminal
number from the ttys(5) file entry.
The ttyname() function returns the NUL-terminated name if the device is
found and isatty() is true; otherwise a null pointer is returned and
errno is set to indicate the error.
The ttyname_r() function returns zero if successful; otherwise an error
number is returned.
The isatty() function returns 1 if fd is associated with a terminal
device; otherwise it returns 0 and errno is set to indicate the error.
The ttyslot() function returns the unit number of the device file if
found; otherwise the value zero is returned.
The ttyname(), ttyname_r(), and isatty() functions will fail if:
[EBADF] The fd argument is not a valid file descriptor.
[ENOTTY] The fd argument does not refer to a terminal device.
[ERANGE] The value of namesize is smaller than the length of
the string to be returned including the terminating
ioctl(2), ttys(5), dev_mkdb(8)
The isatty(), ttyname(), and ttyslot() functions appeared in Version 7
AT&T UNIX. The ttyname_r() function appeared in the POSIX Threads
The ttyname() function leaves its result in an internal static object and
returns a pointer to that object. Subsequent calls to ttyname() will
modify the same object.
OpenBSD 5.1 July 3, 2007 OpenBSD 5.1
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