You can identify the path the the controlling terminal device path for your current process in C with the ttyname() system call. This controlling terminal can be a virtual console (/dev/ttyn) or a pseudo-terminal (/dev/pts/n).

The ttyname system call takes the following format.

char *ttyname(int fd);

The stdin, stdout, stderr file descriptors unless redirected are by default mapped to the controlling terminal. So for example you can pass it the stdin file descriptor.

char * pathname;
pathname = ttyname(0);

printf("controlling terminal : %s\n", pathname);

controlling terminal : /dev/pts/0

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