ctermid − get controlling terminal name

#include <stdio.h>

char *ctermid(char *s);

ctermid() returns a string which is the pathname for the current controlling terminal for this process. If s is NULL, a static buffer is used, otherwise s points to a buffer used to hold the terminal pathname. The symbolic constant L_ctermid is the maximum number of characters in the returned pathname.

The pointer to the pathname.

SVID, Issue 1; POSIX.1

The path returned may not uniquely identify the controlling terminal; it may, for example, be /dev/tty.

It is not assured that the program can open the terminal.

ttyname(3)