.\" Copyright (c) 1993 by Thomas Koenig (ig25@rz.uni-karlsruhe.de)

.\"

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.\" Modified Sat Jul 24 19:51:06 1993 by Rik Faith (faith@cs.unc.edu)

.TH CTERMID 3  2016-03-15 "GNU" "Linux Programmer's Manual"

.SH NAME

ctermid \- get controlling terminal name

.SH SYNOPSIS

.nf

.B #include <stdio.h>

.\" POSIX also requires this function to be declared in <unistd.h>,

.\" and glibc does so if suitable feature test macros are defined.

.PP

.BI "char *ctermid(char *" "s" );

.fi

.PP

.in -4n

Feature Test Macro Requirements for glibc (see

.BR feature_test_macros (7)):

.in

.PP

.BR ctermid ():

_POSIX_C_SOURCE

.SH DESCRIPTION

.BR ctermid ()

returns a string which is the pathname for the current

controlling terminal for this process.

If

.I s

is NULL,

a static buffer is used, otherwise

.I s

points to a buffer used to hold the terminal pathname.

The symbolic constant

.B L_ctermid

is the maximum number of characters in the returned pathname.

.SH RETURN VALUE

The pointer to the pathname.

.SH ATTRIBUTES

For an explanation of the terms used in this section, see

.BR attributes (7).

.TS

allbox;

lb lb lb

l l l.

Interface	Attribute	Value

T{

.BR ctermid ()

T}	Thread safety	MT-Safe

.TE

.SH CONFORMING TO

POSIX.1-2001, POSIX.1-2008, Svr4.

.SH BUGS

The path returned may not uniquely identify the controlling

terminal; it may, for example, be

.IR /dev/tty .

.PP

It is not assured that the program can open the terminal.

.\" in glibc 2.3.x, x >= 4, the glibc headers threw an error

.\" if ctermid() was given an argument; fixed in 2.4.

.SH SEE ALSO

.BR ttyname (3)

.SH COLOPHON

This page is part of release 4.15 of the Linux

.I man-pages

project.

A description of the project,

information about reporting bugs,

and the latest version of this page,

can be found at

\%https://www.kernel.org/doc/man\-pages/.