+++ /dev/null
-.\" Copyright (c) 1995 James R. Van Zandt <jrv@vanzandt.mv.com>
-.\" Sat Feb 18 09:11:07 EST 1995
-.\"
-.\" %%%LICENSE_START(GPLv2+_DOC_FULL)
-.\" This is free documentation; you can redistribute it and/or
-.\" modify it under the terms of the GNU General Public License as
-.\" published by the Free Software Foundation; either version 2 of
-.\" the License, or (at your option) any later version.
-.\"
-.\" The GNU General Public License's references to "object code"
-.\" and "executables" are to be interpreted as the output of any
-.\" document formatting or typesetting system, including
-.\" intermediate and printed output.
-.\"
-.\" This manual is distributed in the hope that it will be useful,
-.\" but WITHOUT ANY WARRANTY; without even the implied warranty of
-.\" MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
-.\" GNU General Public License for more details.
-.\"
-.\" You should have received a copy of the GNU General Public
-.\" License along with this manual; if not, see
-.\" <http://www.gnu.org/licenses/>.
-.\" %%%LICENSE_END
-.\"
-.\" Modified, Sun Feb 26 15:08:05 1995, faith@cs.unc.edu
-.\" 2007-12-17, Samuel Thibault <samuel.thibault@ens-lyon.org>:
-.\" document the VT_GETHIFONTMASK ioctl
-.\" "
-.TH VCS 4 2007-12-17 "Linux" "Linux Programmer's Manual"
-.SH NAME
-vcs, vcsa \- virtual console memory
-.SH DESCRIPTION
-.I /dev/vcs0
-is a character device with major number 7 and minor number
-0, usually of mode 0644 and owner root.tty.
-It refers to the memory of the currently
-displayed virtual console terminal.
-.LP
-.I /dev/vcs[1\-63]
-are character devices for virtual console
-terminals, they have major number 7 and minor number 1 to 63, usually
-mode 0644 and owner root.tty.
-.IR /dev/vcsa[0\-63]
-are the same, but
-using
-.IR "unsigned short" s
-(in host byte order) that include attributes,
-and prefixed with four bytes giving the screen
-dimensions and cursor position:
-.IR lines ,
-.IR columns ,
-.IR x ,
-.IR y .
-.RI ( x
-=
-.I y
-= 0 at the top left corner of the screen.)
-
-When a 512-character font is loaded,
-the 9th bit position can be fetched by applying the
-.BR ioctl (2)
-.B VT_GETHIFONTMASK
-operation
-(available in Linux kernels 2.6.18 and above)
-on
-.IR /dev/tty[1\-63] ;
-the value is returned in the
-.I "unsigned short"
-pointed to by the third
-.BR ioctl (2)
-argument.
-.PP
-These devices replace the screendump
-.BR ioctl (2)
-operations of
-.BR console (4),
-so the system
-administrator can control access using filesystem permissions.
-.PP
-The devices for the first eight virtual consoles may be created by:
-
-.nf
- for x in 0 1 2 3 4 5 6 7 8; do
- mknod \-m 644 /dev/vcs$x c 7 $x;
- mknod \-m 644 /dev/vcsa$x c 7 $[$x+128];
- done
- chown root:tty /dev/vcs*
-.fi
-
-No
-.BR ioctl (2)
-requests are supported.
-.SH FILES
-/dev/vcs[0\-63]
-.br
-/dev/vcsa[0\-63]
-.\" .SH AUTHOR
-.\" Andries Brouwer <aeb@cwi.nl>
-.SH VERSIONS
-Introduced with version 1.1.92 of the Linux kernel.
-.SH EXAMPLE
-You may do a screendump on vt3 by switching to vt1 and typing
-
- cat /dev/vcs3 >foo
-
-Note that the output does not contain
-newline characters, so some processing may be required, like
-in
-
- old \-w 81 /dev/vcs3 | lpr
-
-or (horrors)
-
- xetterm \-dump 3 \-file /proc/self/fd/1
-
-.LP
-The
-.I /dev/vcsa0
-device is used for Braille support.
-
-This program displays the character and screen attributes under the
-cursor of the second virtual console, then changes the background color
-there:
-
-.nf
-#include <unistd.h>
-#include <stdlib.h>
-#include <stdio.h>
-#include <fcntl.h>
-#include <sys/ioctl.h>
-#include <linux/vt.h>
-
-int
-main(void)
-{
- int fd;
- char *device = "/dev/vcsa2";
- char *console = "/dev/tty2";
- struct {unsigned char lines, cols, x, y;} scrn;
- unsigned short s;
- unsigned short mask;
- unsigned char ch, attrib;
-
- fd = open(console, O_RDWR);
- if (fd < 0) {
- perror(console);
- exit(EXIT_FAILURE);
- }
- if (ioctl(fd, VT_GETHIFONTMASK, &mask) < 0) {
- perror("VT_GETHIFONTMASK");
- exit(EXIT_FAILURE);
- }
- (void) close(fd);
- fd = open(device, O_RDWR);
- if (fd < 0) {
- perror(device);
- exit(EXIT_FAILURE);
- }
- (void) read(fd, &scrn, 4);
- (void) lseek(fd, 4 + 2*(scrn.y*scrn.cols + scrn.x), 0);
- (void) read(fd, &s, 2);
- ch = s & 0xff;
- if (attrib & mask)
- ch |= 0x100;
- attrib = ((s & ~mask) >> 8);
- printf("ch=\(aq%c\(aq attrib=0x%02x\\n", ch, attrib);
- attrib ^= 0x10;
- (void) lseek(fd, \-1, 1);
- (void) write(fd, &attrib, 1);
- exit(EXIT_SUCCESS);
-}
-.fi
-.SH SEE ALSO
-.BR console (4),
-.BR tty (4),
-.BR ttyS (4),
-.BR gpm (8)
-.SH COLOPHON
-This page is part of release 3.79 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
-\%http://www.kernel.org/doc/man\-pages/.
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