IOCTL_CONSOLE(2) Linux Programmer's Manual IOCTL_CONSOLE(2)NAME
ioctl_console - ioctls for console terminal and virtual consoles
DESCRIPTION
The following Linux-specific ioctl(2) requests are supported for con‐
sole terminals and virtual consoles. Each requires a third argument,
assumed here to be argp.
KDGETLED
Get state of LEDs. argp points to a char. The lower three bits
of *argp are set to the state of the LEDs, as follows:
LED_CAP 0x04 caps lock led
LED_NUM 0x02 num lock led
LED_SCR 0x01 scroll lock led
KDSETLED
Set the LEDs. The LEDs are set to correspond to the lower three
bits of the unsigned long integer in argp. However, if a higher
order bit is set, the LEDs revert to normal: displaying the
state of the keyboard functions of caps lock, num lock, and
scroll lock.
Before Linux 1.1.54, the LEDs just reflected the state of the corre‐
sponding keyboard flags, and KDGETLED/KDSETLED would also change the
keyboard flags. Since Linux 1.1.54 the LEDs can be made to display
arbitrary information, but by default they display the keyboard flags.
The following two ioctls are used to access the keyboard flags.
KDGKBLED
Get keyboard flags CapsLock, NumLock, ScrollLock (not lights).
argp points to a char which is set to the flag state. The low
order three bits (mask 0x7) get the current flag state, and the
low order bits of the next nibble (mask 0x70) get the default
flag state. (Since Linux 1.1.54.)
KDSKBLED
Set keyboard flags CapsLock, NumLock, ScrollLock (not lights).
argp is an unsigned long integer that has the desired flag
state. The low order three bits (mask 0x7) have the flag state,
and the low order bits of the next nibble (mask 0x70) have the
default flag state. (Since Linux 1.1.54.)
KDGKBTYPE
Get keyboard type. This returns the value KB_101, defined as
0x02.
KDADDIO
Add I/O port as valid. Equivalent to ioperm(arg,1,1).
KDDELIO
Delete I/O port as valid. Equivalent to ioperm(arg,1,0).
KDENABIO
Enable I/O to video board. Equivalent to ioperm(0x3b4,
0x3df-0x3b4+1, 1).
KDDISABIO
Disable I/O to video board. Equivalent to ioperm(0x3b4,
0x3df-0x3b4+1, 0).
KDSETMODE
Set text/graphics mode. argp is an unsigned integer containing
one of:
KD_TEXT 0x00
KD_GRAPHICS 0x01
KDGETMODE
Get text/graphics mode. argp points to an int which is set to
one of the values shown above for KDSETMODE.
KDMKTONE
Generate tone of specified length. The lower 16 bits of the
unsigned long integer in argp specify the period in clock
cycles, and the upper 16 bits give the duration in msec. If the
duration is zero, the sound is turned off. Control returns
immediately. For example, argp = (125<<16) + 0x637 would spec‐
ify the beep normally associated with a ctrl-G. (Thus since
Linux 0.99pl1; broken in Linux 2.1.49-50.)
KIOCSOUND
Start or stop sound generation. The lower 16 bits of argp spec‐
ify the period in clock cycles (that is, argp = 1193180/fre‐
quency). argp = 0 turns sound off. In either case, control
returns immediately.
GIO_CMAP
Get the current default color map from kernel. argp points to a
48-byte array. (Since Linux 1.3.3.)
PIO_CMAP
Change the default text-mode color map. argp points to a
48-byte array which contains, in order, the Red, Green, and Blue
values for the 16 available screen colors: 0 is off, and 255 is
full intensity. The default colors are, in order: black, dark
red, dark green, brown, dark blue, dark purple, dark cyan, light
grey, dark grey, bright red, bright green, yellow, bright blue,
bright purple, bright cyan and white. (Since Linux 1.3.3.)
GIO_FONT
Gets 256-character screen font in expanded form. argp points to
an 8192-byte array. Fails with error code EINVAL if the cur‐
rently loaded font is a 512-character font, or if the console is
not in text mode.
GIO_FONTX
Gets screen font and associated information. argp points to a
struct consolefontdesc (see PIO_FONTX). On call, the charcount
field should be set to the maximum number of characters that
would fit in the buffer pointed to by chardata. On return, the
charcount and charheight are filled with the respective data for
the currently loaded font, and the chardata array contains the
font data if the initial value of charcount indicated enough
space was available; otherwise the buffer is untouched and errno
is set to ENOMEM. (Since Linux 1.3.1.)
PIO_FONT
Sets 256-character screen font. Load font into the EGA/VGA
character generator. argp points to an 8192-byte map, with 32
bytes per character. Only the first N of them are used for an
8xN font (0 < N <= 32). This call also invalidates the Unicode
mapping.
PIO_FONTX
Sets screen font and associated rendering information. argp
points to a
struct consolefontdesc {
unsigned short charcount; /* characters in font
(256 or 512) */
unsigned short charheight; /* scan lines per
character (1-32) */
char *chardata; /* font data in
expanded form */
};
If necessary, the screen will be appropriately resized, and SIG‐
WINCH sent to the appropriate processes. This call also invali‐
dates the Unicode mapping. (Since Linux 1.3.1.)
PIO_FONTRESET
Resets the screen font, size and Unicode mapping to the bootup
defaults. argp is unused, but should be set to NULL to ensure
compatibility with future versions of Linux. (Since Linux
1.3.28.)
GIO_SCRNMAP
Get screen mapping from kernel. argp points to an area of size
E_TABSZ, which is loaded with the font positions used to display
each character. This call is likely to return useless informa‐
tion if the currently loaded font is more than 256 characters.
GIO_UNISCRNMAP
Get full Unicode screen mapping from kernel. argp points to an
area of size E_TABSZ*sizeof(unsigned short), which is loaded
with the Unicodes each character represent. A special set of
Unicodes, starting at U+F000, are used to represent "direct to
font" mappings. (Since Linux 1.3.1.)
PIO_SCRNMAP
Loads the "user definable" (fourth) table in the kernel which
maps bytes into console screen symbols. argp points to an area
of size E_TABSZ.
PIO_UNISCRNMAP
Loads the "user definable" (fourth) table in the kernel which
maps bytes into Unicodes, which are then translated into screen
symbols according to the currently loaded Unicode-to-font map.
Special Unicodes starting at U+F000 can be used to map directly
to the font symbols. (Since Linux 1.3.1.)
GIO_UNIMAP
Get Unicode-to-font mapping from kernel. argp points to a
struct unimapdesc {
unsigned short entry_ct;
struct unipair *entries;
};
where entries points to an array of ,IP
struct unipair {
unsigned short unicode;
unsigned short fontpos;
};
(Since Linux 1.1.92.)
PIO_UNIMAP
Put unicode-to-font mapping in kernel. argp points to a struct
unimapdesc. (Since Linux 1.1.92)
PIO_UNIMAPCLR
Clear table, possibly advise hash algorithm. argp points to a
struct unimapinit {
unsigned short advised_hashsize; /* 0 if no opinion */
unsigned short advised_hashstep; /* 0 if no opinion */
unsigned short advised_hashlevel; /* 0 if no opinion */
};
(Since Linux 1.1.92.)
KDGKBMODE
Gets current keyboard mode. argp points to a long which is set
to one of these:
K_RAW 0x00 /* Raw (scancode) mode */
K_XLATE 0x01 /* Translate keycodes using keymap */
K_MEDIUMRAW 0x02 /* Medium raw (scancode) mode */
K_UNICODE 0x03 /* Unicode mode */
K_OFF 0x04 /* Disabled mode; since Linux 2.6.39 */
KDSKBMODE
Sets current keyboard mode. argp is a long equal to one of the
values shown for KDGKBMODE.
KDGKBMETA
Gets meta key handling mode. argp points to a long which is set
to one of these:
K_METABIT 0x03 set high order bit
K_ESCPREFIX 0x04 escape prefix
KDSKBMETA
Sets meta key handling mode. argp is a long equal to one of the
values shown above for KDGKBMETA.
KDGKBENT
Gets one entry in key translation table (keycode to action
code). argp points to a
struct kbentry {
unsigned char kb_table;
unsigned char kb_index;
unsigned short kb_value;
};
with the first two members filled in: kb_table selects the key
table (0 <= kb_table < MAX_NR_KEYMAPS), and kb_index is the key‐
code (0 <= kb_index < NR_KEYS). kb_value is set to the corre‐
sponding action code, or K_HOLE if there is no such key, or
K_NOSUCHMAP if kb_table is invalid.
KDSKBENT
Sets one entry in translation table. argp points to a struct
kbentry.
KDGKBSENT
Gets one function key string. argp points to a
struct kbsentry {
unsigned char kb_func;
unsigned char kb_string[512];
};
kb_string is set to the (null-terminated) string corresponding
to the kb_functh function key action code.
KDSKBSENT
Sets one function key string entry. argp points to a struct
kbsentry.
KDGKBDIACR
Read kernel accent table. argp points to a
struct kbdiacrs {
unsigned int kb_cnt;
struct kbdiacr kbdiacr[256];
};
where kb_cnt is the number of entries in the array, each of
which is a
struct kbdiacr {
unsigned char diacr;
unsigned char base;
unsigned char result;
};
KDGETKEYCODE
Read kernel keycode table entry (scan code to keycode). argp
points to a
struct kbkeycode {
unsigned int scancode;
unsigned int keycode;
};
keycode is set to correspond to the given scancode. (89 <=
scancode <= 255 only. For 1 <= scancode <= 88, keycode==scan‐
code.) (Since Linux 1.1.63.)
KDSETKEYCODE
Write kernel keycode table entry. argp points to a struct kbk‐
eycode. (Since Linux 1.1.63.)
KDSIGACCEPT
The calling process indicates its willingness to accept the sig‐
nal argp when it is generated by pressing an appropriate key
combination. (1 <= argp <= NSIG). (See spawn_console() in
linux/drivers/char/keyboard.c.)
VT_OPENQRY
Returns the first available (non-opened) console. argp points
to an int which is set to the number of the vt (1 <= *argp <=
MAX_NR_CONSOLES).
VT_GETMODE
Get mode of active vt. argp points to a
struct vt_mode {
char mode; /* vt mode */
char waitv; /* if set, hang on writes if not active */
short relsig; /* signal to raise on release req */
short acqsig; /* signal to raise on acquisition */
short frsig; /* unused (set to 0) */
};
which is set to the mode of the active vt. mode is set to one
of these values:
VT_AUTO auto vt switching
VT_PROCESS process controls switching
VT_ACKACQ acknowledge switch
VT_SETMODE
Set mode of active vt. argp points to a struct vt_mode.
VT_GETSTATE
Get global vt state info. argp points to a
struct vt_stat {
unsigned short v_active; /* active vt */
unsigned short v_signal; /* signal to send */
unsigned short v_state; /* vt bit mask */
};
For each vt in use, the corresponding bit in the v_state member
is set. (Kernels 1.0 through 1.1.92.)
VT_RELDISP
Release a display.
VT_ACTIVATE
Switch to vt argp (1 <= argp <= MAX_NR_CONSOLES).
VT_WAITACTIVE
Wait until vt argp has been activated.
VT_DISALLOCATE
Deallocate the memory associated with vt argp. (Since Linux
1.1.54.)
VT_RESIZE
Set the kernel's idea of screensize. argp points to a
struct vt_sizes {
unsigned short v_rows; /* # rows */
unsigned short v_cols; /* # columns */
unsigned short v_scrollsize; /* no longer used */
};
Note that this does not change the videomode. See resize‐
cons(8). (Since Linux 1.1.54.)
VT_RESIZEX
Set the kernel's idea of various screen parameters. argp points
to a
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 */
};
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 resizecons(8).
(Since Linux 1.3.3.)
The action of the following ioctls depends on the first byte in the
struct pointed to by argp, referred to here as the subcode. These are
legal only for the superuser or the owner of the current terminal.
TIOCLINUX, subcode=0
Dump the screen. Disappeared in Linux 1.1.92. (With kernel
1.1.92 or later, read from /dev/vcsN or /dev/vcsaN instead.)
TIOCLINUX, subcode=1
Get task information. Disappeared in Linux 1.1.92.
TIOCLINUX, subcode=2
Set selection. argp points to a
struct {
char subcode;
short xs, ys, xe, ye;
short sel_mode;
};
xs and ys are the starting column and row. xe and ye are the
ending column and row. (Upper left corner is row=column=1.)
sel_mode is 0 for character-by-character selection, 1 for word-
by-word selection, or 2 for line-by-line selection. The indi‐
cated screen characters are highlighted and saved in the static
array sel_buffer in devices/char/console.c.
TIOCLINUX, subcode=3
Paste selection. The characters in the selection buffer are
written to fd.
TIOCLINUX, subcode=4
Unblank the screen.
TIOCLINUX, subcode=5
Sets contents of a 256-bit look up table defining characters in
a "word", for word-by-word selection. (Since Linux 1.1.32.)
TIOCLINUX, subcode=6
argp points to a char which is set to the value of the kernel
variable shift_state. (Since Linux 1.1.32.)
TIOCLINUX, subcode=7
argp points to a char which is set to the value of the kernel
variable report_mouse. (Since Linux 1.1.33.)
TIOCLINUX, subcode=8
Dump screen width and height, cursor position, and all the char‐
acter-attribute pairs. (Kernels 1.1.67 through 1.1.91 only.
With kernel 1.1.92 or later, read from /dev/vcsa* instead.)
TIOCLINUX, subcode=9
Restore screen width and height, cursor position, and all the
character-attribute pairs. (Kernels 1.1.67 through 1.1.91 only.
With kernel 1.1.92 or later, write to /dev/vcsa* instead.)
TIOCLINUX, subcode=10
Handles the Power Saving feature of the new generation of moni‐
tors. VESA screen blanking mode is set to argp[1], which gov‐
erns what screen blanking does:
0: Screen blanking is disabled.
1: The current video adapter register settings are saved, then
the controller is programmed to turn off the vertical syn‐
chronization pulses. This puts the monitor into "standby"
mode. If your monitor has an Off_Mode timer, then it will
eventually power down by itself.
2: The current settings are saved, then both the vertical and
horizontal synchronization pulses are turned off. This puts
the monitor into "off" mode. If your monitor has no Off_Mode
timer, or if you want your monitor to power down immediately
when the blank_timer times out, then you choose this option.
(Caution: Powering down frequently will damage the monitor.)
(Since Linux 1.1.76.)
RETURN VALUE
On success, 0 is returned. On error, -1 is returned, and errno is set.
ERRORS
errno may take on these values:
EBADF The file descriptor is invalid.
EINVAL The file descriptor or argp is invalid.
ENOTTY The file descriptor is not associated with a character special
device, or the specified request does not apply to it.
EPERM Insufficient permission.
NOTES
Warning: Do not regard this man page as documentation of the Linux con‐
sole ioctls. This is provided for the curious only, as an alternative
to reading the source. Ioctl's are undocumented Linux internals,
liable to be changed without warning. (And indeed, this page more or
less describes the situation as of kernel version 1.1.94; there are
many minor and not-so-minor differences with earlier versions.)
Very often, ioctls are introduced for communication between the kernel
and one particular well-known program (fdisk, hdparm, setserial,
tunelp, loadkeys, selection, setfont, etc.), and their behavior will be
changed when required by this particular program.
Programs using these ioctls will not be portable to other versions of
UNIX, will not work on older versions of Linux, and will not work on
future versions of Linux.
Use POSIX functions.
SEE ALSOdumpkeys(1), kbd_mode(1), loadkeys(1), mknod(1), setleds(1), setmeta‐
mode(1), execve(2), fcntl(2), ioctl_tty(2), ioperm(2), termios(3), con‐
sole_codes(4), mt(4), sd(4), tty(4), ttyS(4), vcs(4), vcsa(4),
charsets(7), mapscrn(8), resizecons(8), setfont(8)
/usr/include/linux/kd.h, /usr/include/linux/vt.h
COLOPHON
This page is part of release 4.14 of the Linux 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/.
Linux 2017-09-15 IOCTL_CONSOLE(2)
