ctermid, ctermid_r - generate path name for controlling terminal
char *ctermid(char *s);
char *ctermid_r(char *s);
The ctermid() function generates the path name of the controlling ter‐
minal 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 multi‐
See attributes(5) for descriptions of the following attributes:
│ ATTRIBUTE TYPE │ ATTRIBUTE VALUE │
│Interface Stability │ ctermid() is Standard │
│MT-Level │ ctermid() is Unsafe; cter‐ │
│ │ mid_r() is MT-Safe │
SEE ALSOttyname(3C), attributes(5)
Jul 25, 2000 CTERMID(3C)