TTYNAME(3) Library Functions Manual TTYNAME(3)

ttyname, ttyname_r, isattyget name of associated terminal (tty) from file descriptor

Standard C Library (libc, -lc)

#include <unistd.h>

char *
ttyname(int fd);

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

isatty(int fd);

These functions operate on file descriptors for terminal type devices.

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

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

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

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.

These functions may fail if:

The fd argument is not a valid file descriptor.
The file associated with fd is not a terminal.

Additionally, ttyname_r() may fail if:

The bufsize argument is smaller than the length of the string to be returned.

ioctl(2), ptsname(3), tcgetattr(3), tty(4), ttys(5)

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

July 18, 2014 macOS 14.3