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.Dd June 4, 1993
.Dt CTERMID 3
.Os
.Sh NAME
.Nm ctermid
.Nd generate terminal pathname
.Sh SYNOPSIS
.Fd #include <stdio.h>
.Ft char *
.Fn ctermid "char *buf"
.Sh DESCRIPTION
The
.Fn ctermid
function generates a string, that, when used as a pathname, refers to
the current controlling terminal of the calling process.
.Pp
If
.Ar buf
is a null pointer, a pointer to a static area is returned.
Otherwise, the pathname is copied into the memory referenced by
.Ar buf .
The argument
.Ar buf
is assumed to point to an array at least
.Dv L_ctermid
(as defined in the include
file
.Aq Pa stdio.h )
bytes long.
.Pp
The current implementation simply generates
.Qq /dev/tty .
.Sh RETURN VALUES
Upon successful completion, a non-null pointer is returned.
Otherwise, a null pointer is returned and the global variable
.Va errno
is set to indicate the error.
.Sh ERRORS
The current implementation detects no error conditions.
.Sh SEE ALSO
.Xr ttyname 3
.Sh STANDARDS
The
.Fn ctermid
function conforms to
.St -p1003.1-88 .
.Sh BUGS
By default the
.Fn ctermid
function writes all information to an internal static object.
Subsequent calls to
.Fn ctermid
will modify the same object.