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<A NAME="PAGENUM-1102"><P>Page 1102</P></A>
<P>These replace the screendump ioctls of console(4), so the system administrator can control access using filesystem
permissions.
</P>
<P>The devices for the first eight virtual consoles may be created by
</P>
<!-- CODE SNIP //-->
<PRE>
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*
</PRE>
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<P>No ioctl() requests are supported.
</P>
<P><B>
EXAMPLES
</B></P>
<P>You can do a screendump on vt3 by switching to vt1 and typing
cat /dev/vcs3 >foo.
</P>
<P>This program displays the character and screen attributes under the cursor of the second virtual console and then changes
the background color there:
</P>
<!-- CODE //-->
<PRE>
#include <unistd.h>
#include <stdio.h>
#include <fcntl.h>
void main()
{ int fd;
struct {char lines, cols, x, y;} scrn;
char ch, attrib;
fd = open("/dev/vcsa2", O_RDWR);
(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);
}
</PRE>
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<P><B>
FILES
</B></P>
<!-- CODE SNIP //-->
<PRE>
/dev/vcs[0-63]
/dev/vcsa[0-63]
</PRE>
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<P><B>
AUTHOR
</B></P>
<P>Andries Brouwer (aeb@cwi.nl)
</P>
<P><B>
HISTORY
</B></P>
<P>Introduced with version 1.1.92 of the Linux kernel.
</P>
<P><B>
SEE ALSO
</B></P>
<P>console(4), tty(4), ttys(4), selection(1)
</P>
<P>Linux, 19 February 1995
</P>
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