vcstime(8) [linux man page]

VCSTIME(8)							Linux User's Manual							VCSTIME(8)

NAME

       vcstime - Show time in upper right hand corner of the console screen

SYNOPSIS

       vcstime

DESCRIPTION

       vcstime shows the current time in the upper right-hand corner of the console screen.

       This simple program shows the current time in the corner of the console screen.

       It needs to be run by root, in order to have write permissions to /dev/vcsa

AUTHORS

       vcstime	was  written  by  Andries Brouwer, based on  a suggestion by Miguel de Icaza.  This manual page was Written by Alastair McKinstry,
       Debian, Jan 2003.

Console tools							    22 Jan 2003 							VCSTIME(8)

VCS(4)							     Linux Programmer's Manual							    VCS(4)

NAME

       vcs, vcsa - virtual console memory

DESCRIPTION

       /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.

       /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.  /dev/vcsa[0-63] are the same, but including attributes, and prefixed with four bytes giving the screen dimensions and
       cursor position: lines, columns, x, y.  (x = y = 0 at the top left corner of the screen.)

       These replace the screendump ioctls of console(4), so the system administrator can control access using file system permissions.

       The devices for the first eight virtual consoles may be created by:

	    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*

       No ioctl() requests are supported.

EXAMPLES

       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 fold -w 81 /dev/vcs3 | lpr or (horrors) setterm -dump 3 -file /proc/self/fd/1.

       The /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:

	    #include <unistd.h>
	    #include <stdio.h>
	    #include <fcntl.h>

	    int 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
", ch, attrib);
		 attrib ^= 0x10;
		 (void)lseek(fd, -1, 1);
		 (void)write(fd, &attrib, 1);
		 return 0;
	    }

FILES

       /dev/vcs[0-63]
       /dev/vcsa[0-63]

AUTHOR

       Andries Brouwer <aeb@cwi.nl>

HISTORY

       Introduced with version 1.1.92 of the Linux kernel.

SEE ALSO

       console(4), tty(4), ttys(4), selection(1)

Linux								    1995-02-19								    VCS(4)