'\" t
.\" Copyright 1995, James R. Van Zandt <jrv@vanzandt.mv.com>
.\" Copyright 1995, Andries E. Brouwer <aeb@cwi.nl>
.\" Copyright 1995, Rickard E. Faith <faith@cs.unc.edu>
.\" Copyright 1995, H. Peter Anvin <hpa@storm.net>
.\" Copyright, the authors of the Linux man-pages project
.\"
.\" SPDX-License-Identifier: GPL-2.0-or-later
.\"
.\" FIXME The following are not documented:
.\"     VT_LOCKSWITCH (since Linux 1.3.47, needs CAP_SYS_TTY_CONFIG)
.\"     VT_UNLOCKSWITCH (since Linux 1.3.47, needs CAP_SYS_TTY_CONFIG)
.\"     VT_GETHIFONTMASK (since Linux 2.6.18)
.\"
.TH ioctl_vt 2 2026-02-08 "Linux man-pages 6.19"
.SH NAME
ioctl_vt
\-
ioctls for console terminal and virtual consoles
.SH SYNOPSIS
.nf
.BR "#include <linux/vt.h>" "  /* Definition of " VT_* " constants */"
.B #include <sys/ioctl.h>
.P
.BI "int ioctl(int " fd ", unsigned long " op ", void *" argp );
.fi
.SH DESCRIPTION
The following Linux-specific
.BR ioctl (2)
operations are supported for console terminals and virtual consoles.
.TP
.B VT_OPENQRY
Returns the first available (non-opened) console.
.I argp
points to an
.I int
which is set to the
number of the vt (1 <=
.I *argp
<= MAX_NR_CONSOLES).
.TP
.B VT_GETMODE
Get mode of active vt.
.I argp
points to a
.IP
.in +4n
.EX
struct vt_mode {
    char  mode;    /* vt mode */
    char  waitv;   /* if set, hang on writes if not active */
    short relsig;  /* signal to raise on release op */
    short acqsig;  /* signal to raise on acquisition */
    short frsig;   /* unused (set to 0) */
};
.EE
.in
.IP
which is set to the mode of the active vt.
.I mode
is set to one of these values:
.TS
l l.
VT_AUTO	auto vt switching
VT_PROCESS	process controls switching
VT_ACKACQ	acknowledge switch
.TE
.TP
.B VT_SETMODE
Set mode of active vt.
.I argp
points to a
.IR "struct vt_mode" .
.TP
.B VT_GETSTATE
Get global vt state info.
.I argp
points to a
.IP
.in +4n
.EX
struct vt_stat {
    unsigned short v_active;  /* active vt */
    unsigned short v_signal;  /* signal to send */
    unsigned short v_state;   /* vt bit mask */
};
.EE
.in
.IP
For each vt in use, the corresponding bit in the
.I v_state
member is set.
(Linux 1.0 through Linux 1.1.92.)
.TP
.B VT_RELDISP
Release a display.
.TP
.B VT_ACTIVATE
Switch to vt
.I argp
(1 <=
.I argp
<= MAX_NR_CONSOLES).
.TP
.B VT_WAITACTIVE
Wait until vt
.I argp
has been activated.
.TP
.B VT_DISALLOCATE
Deallocate the memory associated with vt
.IR argp .
(Since Linux 1.1.54.)
.TP
.B VT_RESIZE
Set the kernel's idea of screensize.
.I argp
points to a
.IP
.in +4n
.EX
struct vt_sizes {
    unsigned short v_rows;       /* # rows */
    unsigned short v_cols;       /* # columns */
    unsigned short v_scrollsize; /* no longer used */
};
.EE
.in
.IP
Note that this does not change the videomode.
See
.BR resizecons (8).
(Since Linux 1.1.54.)
.TP
.B VT_RESIZEX
Set the kernel's idea of various screen parameters.
.I argp
points to a
.IP
.in +4n
.EX
struct vt_consize {
    unsigned short v_rows;  /* number of rows */
    unsigned short v_cols;  /* number of columns */
    unsigned short v_vlin;  /* number of pixel rows
                               on screen */
    unsigned short v_clin;  /* number of pixel rows
                               per character */
    unsigned short v_vcol;  /* number of pixel columns
                               on screen */
    unsigned short v_ccol;  /* number of pixel columns
                               per character */
};
.EE
.in
.IP
Any parameter may be set to zero, indicating "no change", but if
multiple parameters are set, they must be self-consistent.
Note that this does not change the videomode.
See
.BR resizecons (8).
(Since Linux 1.3.3.)
.TP
.B VT_GETCONSIZECSRPOS
Get console size and cursor position.
.I argp
points to a
.IP
.in +4n
.EX
struct vt_consizecsrpos {
    __u16 con_rows;  /* number of console rows */
    __u16 con_cols;  /* number of console columns */
    __u16 csr_row;   /* current cursor's row */
    __u16 csr_col;   /* current cursor's column */
};
.EE
.in
.IP
(Since Linux 6.16.)
.SH RETURN VALUE
On success, 0 is returned (except where indicated).
On failure, \-1 is returned, and
.I errno
is set to indicate the error.
.SH ERRORS
.TP
.B EINVAL
.I argp
is invalid.
.SH STANDARDS
Linux.
.SH SEE ALSO
.BR ioctl (2),
.BR ioctl_console (2)