The ttyname() function returns a pointer to a string containing the null-terminated path name of the terminal device associated with file descriptor fildes. The return value may point to static data whose content is overwritten by each call.

The ttyname_r() function has the same functionality as ttyname() except that the caller must supply a buffer name with length namelen to store the result; this buffer must be at least _POSIX_PATH_MAX in size (defined in <limits.h>). The POSIX version (see standards(5)) of ttyname_r() takes a namesize parameter of type size_t.

Upon successful completion, ttyname() and ttyname_r() return a pointer to a string. Otherwise, a null pointer is returned and errno is set to indicate the error.

The POSIX ttyname_r() returns zero if successful, or the error number upon failure.

The ttyname_r() function will fail if:

ERANGE

The size of the buffer is smaller than the result to be returned.

The ttyname() function may fail if:

EBADF

The fildes argument is not a valid file descriptor.

ENOTTY

The fildes argument does not refer to a terminal device.

/dev/*

device file

See attributes(5) for descriptions of the following attributes:

Intro(3), gettext(3C), setlocale(3C), attributes(5), standards(5)

When compiling multithreaded programs, see Intro(3), Notes On Multithreaded Applications.

If the application is linked with -lintl, then messages printed from this function are in the native language specified by the LC_MESSAGES locale category; see setlocale(3C).

The return value points to static data whose content is overwritten by each call.

The ttyname() is Unsafe in multithreaded applications. The ttyname_r() function is MT-Safe, and should be used instead.

Solaris 2.4 and earlier releases provided definitions of the ttyname_r() interface as specified in POSIX.1c Draft 6. The final POSIX.1c standard changed the interface as described above. Support for the Draft 6 interface is provided for compatibility only and may not be supported in future releases. New applications and libraries should use the POSIX standard interface.