CTERMID(3C) Standard C Library Functions CTERMID(3C)


ctermid, ctermid_r - generate path name for controlling terminal


#include <stdio.h>

char *ctermid(char *s);

char *ctermid_r(char *s);


The ctermid() function generates the path name of the controlling
terminal for the current process and stores it in a string.

If s is a null pointer, the string is stored in an internal static area
whose address is returned and whose contents are overwritten at the next
call to ctermid(). Otherwise, s is assumed to point to a character array
of at least L_ctermid elements. The path name is placed in this array and
the value of s is returned. The constant L_ctermid is defined in the
header <stdio.h>.

The ctermid_r() function behaves as ctermid() except that if s is a null
pointer, the function returns NULL.


The difference between ctermid() and ttyname(3C) is that ttyname() must
be passed a file descriptor and returns the actual name of the terminal
associated with that file descriptor, while ctermid() returns a string
(/dev/tty) that will refer to the terminal if used as a file name. The
ttyname() function is useful only if the process already has at least one
file open to a terminal.

The ctermid() function is unsafe in multithreaded applications. The
ctermid_r() function is MT-Safe and should be used instead.

When compiling multithreaded applications, the _REENTRANT flag must be
defined on the compile line. This flag should be used only with
multithreaded applications.


See attributes(7) for descriptions of the following attributes:

|Interface Stability | ctermid() is Standard |
|MT-Level | ctermid() is Unsafe; |
| | ctermid_r() is MT-Safe |


ttyname(3C), attributes(7)

July 25, 2000 CTERMID(3C)