NAME

ttyname, ttyname_r, isatty —

get name of associated terminal (tty) from file descriptor

LIBRARY

Standard C Library (libc, -lc)

SYNOPSIS

#include <unistd.h>

char *
ttyname(int fd);

int
ttyname_r(int fd, char *buf, size_t len);

int
isatty(int fd);

DESCRIPTION

These functions operate on file descriptors for terminal type devices.

The isatty() function determines if the file descriptor fd refers to a valid terminal type device.

The ttyname() function gets the related device name of a file descriptor for which isatty() is true.

The ttyname() function returns the name stored in a static buffer which will be overwritten on subsequent calls. The ttyname_r() function takes a buffer and length as arguments to avoid this problem.

RETURN VALUES

The isatty() function returns 1 if fd refers to a terminal type device; otherwise, it returns 0 and may set errno to indicate the error. The ttyname() function returns the null terminated name if the device is found and isatty() is true; otherwise a NULL pointer is returned. The ttyname_r() function returns 0 if successful. Otherwise an error number is returned.

ERRORS

These functions may fail if:

[EBADF]: The fd argument is not a valid file descriptor.
[ENOTTY]: The file associated with fd is not a terminal.

Additionally, ttyname_r() may fail if:

[ERANGE]: The bufsize argument is smaller than the length of the string to be returned.

HISTORY

The isatty() and ttyname() functions appeared in Version 7 AT&T UNIX. The ttyname_r() function appeared in FreeBSD 6.0.