2004-11-03 13:51:07 +00:00
|
|
|
.\" Copyright (c) 1995 James R. Van Zandt <jrv@vanzandt.mv.com>
|
|
|
|
.\" Sat Feb 18 09:11:07 EST 1995
|
|
|
|
.\"
|
|
|
|
.\" 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, write to the Free
|
|
|
|
.\" Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111,
|
|
|
|
.\" USA.
|
|
|
|
.\"
|
|
|
|
.\" Modified, Sun Feb 26 15:08:05 1995, faith@cs.unc.edu
|
|
|
|
.\" "
|
|
|
|
.TH VCS 4 1995-02-19 "Linux" "Linux Programmer's Manual"
|
|
|
|
.SH NAME
|
|
|
|
vcs, vcsa \- virtual console memory
|
|
|
|
.SH DESCRIPTION
|
2005-11-02 13:55:25 +00:00
|
|
|
\fI/dev/vcs0\fP is a character device with major number 7 and minor number
|
2004-11-03 13:51:07 +00:00
|
|
|
0, usually of mode 0644 and owner root.tty. It refers to the memory
|
|
|
|
of the currently
|
|
|
|
displayed virtual console terminal.
|
|
|
|
.LP
|
2005-11-02 13:55:25 +00:00
|
|
|
\fI/dev/vcs[1\-63]\fP are character devices for virtual console
|
2004-11-03 13:51:07 +00:00
|
|
|
terminals, they have major number 7 and minor number 1 to 63, usually
|
2005-11-02 13:55:25 +00:00
|
|
|
mode 0644 and owner root.tty. \fI/dev/vcsa[0\-63]\fP are the same, but
|
2004-11-03 13:51:07 +00:00
|
|
|
including attributes, and prefixed with four bytes giving the screen
|
|
|
|
dimensions and cursor position: \fIlines\fP, \fIcolumns\fP, \fIx\fP, \fIy\fP.
|
|
|
|
(\fIx\fP = \fIy\fP = 0 at the top left corner of the screen.)
|
|
|
|
.PP
|
|
|
|
These replace the screendump
|
|
|
|
.IR ioctl s
|
|
|
|
of \fBconsole\fP(4), so the system
|
|
|
|
administrator can control access using file system permissions.
|
|
|
|
.PP
|
|
|
|
The devices for the first eight virtual consoles may be created by:
|
|
|
|
|
|
|
|
.nf
|
2006-05-22 19:44:47 +00:00
|
|
|
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*
|
2004-11-03 13:51:07 +00:00
|
|
|
.fi
|
|
|
|
|
|
|
|
No
|
2005-11-02 11:34:24 +00:00
|
|
|
.BR ioctl ()
|
2004-11-03 13:51:07 +00:00
|
|
|
requests are supported.
|
2006-05-22 19:44:47 +00:00
|
|
|
.SH EXAMPLE
|
2004-11-03 13:51:07 +00:00
|
|
|
You may do a screendump on vt3 by switching to vt1 and typing
|
|
|
|
\fIcat /dev/vcs3 >foo\fP. Note that the output does not contain
|
|
|
|
newline characters, so some processing may be required, like
|
2005-07-06 07:41:37 +00:00
|
|
|
in \fIfold \-w 81 /dev/vcs3 | lpr\fP or (horrors)
|
|
|
|
\fIsetterm \-dump 3 \-file /proc/self/fd/1\fP.
|
2004-11-03 13:51:07 +00:00
|
|
|
.LP
|
|
|
|
The \fI/dev/vcsa0\fP 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
|
2006-05-22 19:44:47 +00:00
|
|
|
#include <unistd.h>
|
|
|
|
#include <stdlib.h>
|
|
|
|
#include <stdio.h>
|
|
|
|
#include <fcntl.h>
|
2004-11-03 13:51:07 +00:00
|
|
|
|
2006-05-22 19:44:47 +00:00
|
|
|
int main() {
|
|
|
|
int fd;
|
|
|
|
char *device = "/dev/vcsa2";
|
|
|
|
struct {unsigned char lines, cols, x, y;} scrn;
|
|
|
|
char ch, attrib;
|
2004-11-03 13:51:07 +00:00
|
|
|
|
2006-05-22 19:44:47 +00:00
|
|
|
fd = open(device, O_RDWR);
|
|
|
|
if (fd < 0) {
|
|
|
|
perror(device);
|
|
|
|
exit(1);
|
|
|
|
}
|
|
|
|
(void) read(fd, &scrn, 4);
|
|
|
|
(void) lseek(fd, 4 + 2*(scrn.y*scrn.cols + scrn.x), 0);
|
|
|
|
(void) read(fd, &ch, 1);
|
|
|
|
(void) read(fd, &attrib, 1);
|
|
|
|
printf("ch='%c' attrib=0x%02x\\n", ch, attrib);
|
|
|
|
attrib ^= 0x10;
|
|
|
|
(void) lseek(fd, \-1, 1);
|
|
|
|
(void) write(fd, &attrib, 1);
|
|
|
|
return 0;
|
|
|
|
}
|
2004-11-03 13:51:07 +00:00
|
|
|
.fi
|
|
|
|
|
|
|
|
.SH FILES
|
2005-07-07 08:27:03 +00:00
|
|
|
/dev/vcs[0\-63]
|
2004-11-03 13:51:07 +00:00
|
|
|
.br
|
2005-07-07 08:27:03 +00:00
|
|
|
/dev/vcsa[0\-63]
|
2004-11-03 13:51:07 +00:00
|
|
|
.SH AUTHOR
|
|
|
|
Andries Brouwer <aeb@cwi.nl>
|
|
|
|
.SH HISTORY
|
|
|
|
Introduced with version 1.1.92 of the Linux kernel.
|
|
|
|
.SH "SEE ALSO"
|
2005-06-24 11:59:32 +00:00
|
|
|
.BR gpm (8),
|
2004-11-03 13:51:07 +00:00
|
|
|
.BR console (4),
|
|
|
|
.BR tty (4),
|
2005-05-11 14:18:48 +00:00
|
|
|
.BR ttyS (4)
|