Identification of controlling terminal.
| Syntax | 
|  | 
| 
   #include <stdio.h>
   char *ctermid(char *s);
 | 
| Parameters | 
|  | 
- s
- 
The address of an array that will receive the pathname fo the current controlling terminal.
 
| Return Values | 
|  | 
If s is not NULL then it points to an array of char L_ctermid bytes long, or longer, as defined in <stdio.h>.
An empty string is returned if the ctermid() function is unsuccessful.
| Description | 
|  | 
The ctermid() function returns a string that can be used as a filename for referencing a terminal.
If a pathname is returned, access is not guaranteed.
| Implementation Considerations | 
|  | 
None.
| Errors | 
|  | 
None.
| See Also | 
|  | 
ttyname(), POSIX.1 (Section 4.7.2)