'\" t
.\" Copyright 2006-2015, Michael Kerrisk <mtk.manpages@gmail.com>
.\" Copyright, the authors of the Linux man-pages project
.\"
.\" SPDX-License-Identifier: GPL-2.0-or-later
.\"
.TH tcsetattr 3 2026-07-02 "Linux man-pages 6.19"
.SH NAME
tcgetattr, tcsetattr
\-
get and set terminal attributes
.SH LIBRARY
Standard C library
.RI ( libc ,\~ \-lc )
.SH SYNOPSIS
.nf
.B #include <termios.h>
.P
.BI "int tcgetattr(int " fd ", struct termios *" termios_p );
.BI "int tcsetattr(int " fd ", int " optional_actions ,
.BI "              const struct termios *" termios_p );
.fi
.SH DESCRIPTION
.BR tcgetattr ()
gets the parameters associated with the object referred by
.IR fd ,
and stores them in the
.I termios
structure referenced by
.IR termios_p .
This function may be invoked from a background process;
however,
the terminal attributes may be subsequently changed
by a foreground process.
.P
.BR tcsetattr ()
sets the parameters associated with the terminal
(unless support is required from the underlying hardware that is not available)
from the
.I termios
structure referred to by
.IR termios_p .
.I optional_actions
specifies when the changes take effect:
.TP
.B TCSANOW
the change occurs immediately.
.TP
.B TCSADRAIN
the change occurs after all output written to
.I fd
has been transmitted.
This option should be used when changing
parameters that affect output.
.TP
.B TCSAFLUSH
the change occurs after all output written to the object referred by
.I fd
has been transmitted,
and all input that has been received but not read
will be discarded before the change is made.
.SH RETURN VALUE
.TP
.B 0
on success.
.TP
.B \-1
on failure and set
.I errno
to indicate the error.
.SH ATTRIBUTES
For an explanation of the terms used in this section,
see
.BR attributes (7).
.TS
allbox;
lbx lb lb
l l l.
Interface	Attribute	Value
T{
.na
.nh
.BR tcgetattr (),
.BR tcsetattr ()
T}	Thread safety	MT-Safe
.TE
.SH STANDARDS
POSIX.1-2008.
.SH HISTORY
POSIX.1-2001.
.SH CAVEATS
.BR tcsetattr ()
returns success if
.I any
of the requested changes could be
successfully carried out.
Therefore,
when making multiple changes,
it may be necessary to follow this call with a further call to
.BR tcgetattr ()
to check that all changes have been performed successfully.
.SH SEE ALSO
.BR termios (3type),
.BR termios (7)