ctermid - generate pathname for controlling terminal

Syntax	#include <stdio.h> char *ctermid(char *s);
Description	ctermid() generates a string that, when used as a pathname, refers to the current controlling terminal for the current process. If s is a null pointer, the string is generated in an internal static area that is overwritten by the each call to ctermid(), and the address of this area is returned. Otherwise, s is assumed to point to a character array of at least L_ctermid elements; the pathname is placed in this array and the value of s is returned. The symbolic constant L_ctermid is defined in the header file stdio.h.
Return val.	In non-conformance with the XPG4 standard, /dev/tty is always returned.
Notes	The difference between ctermid() and ttyname() is that ttyname() must be handed a file descriptor and returns the pathname of the terminal associated with that file descriptor, while ctermid() returns a string (such as /dev/tty) that will refer to the current controlling terminal if used as a pathname. In other words, ttyname() is only useful if the process has already opened at least one file for a terminal.
See also	ttyname(), stdio.h.