SYNOPSIS

     #include <stdio.h>

     char *
     ctermid(char *buf);

     char *
     ctermid_r(char *buf);

DESCRIPTION

     The ctermid() function generates a string, that, when used as a pathname,
     refers to the current controlling terminal of the calling process.

     If buf is the NULL pointer, a pointer to a static area is returned.  Oth-
     erwise, the pathname is copied into the memory referenced by buf.  The
     argument buf is assumed to be at least L_ctermid (as defined in the
     include file <stdio.h>) bytes long.

     The ctermid_r() function provides the same functionality as ctermid()
     except that if buf is a NULL pointer, NULL is returned.

     The current implementation simply returns `/dev/tty'.

RETURN VALUES

     Upon successful completion, a non-NULL pointer is returned.  Otherwise, a
     NULL pointer is returned and the global variable errno is set to indicate
     the error.

ERRORS

     The current implementation detects no error conditions.

SEE ALSO

     ttyname(3)

STANDARDS

     The ctermid() function conforms to IEEE Std 1003.1-1988 (``POSIX.1'').

BUGS

     By default the ctermid() function writes all information to an internal
     static object.  Subsequent calls to ctermid() will modify the same
     object.

BSD                              June 4, 1993                              BSD