screendu(8) [minix man page]

SCREENDUMP(8)						      System Manager's Manual						     SCREENDUMP(8)

NAME

       screendump - write current console screen to standard output

SYNOPSIS

       screendump

DESCRIPTION

       Screendump  prints  the	contents  of  the  console  screen  to	standard output.  It does this by reading the screen memory, skipping over
       attribute bytes, omitting trailing blanks and inserting a newline character at the end of each line.

NOTES

       The most common use of screendump is with output redirected to a file. This allows screen displays (including output of F-keys) to be  cap-
       tured for inclusion in other documents.

       This version is for IBM-PC architecture only.

BUGS

       A  network  user  captures  an image of the main console, not his or her own screen.  The output will usually not be what you expect if the
       display is in hardware scrolling mode, since in that mode the order of the lines in screen memory may not be the same as  what  appears	on
       the screen.  If you expect to use screendump to send notes to someone about problems that occur while using MINIX you must remember to tog-
       gle to software scrolling before you make the dump.  It will also be necessary to use su, because /dev/mem is normally not world readable.

AUTHOR

       Kees J. Bot (kjb@cs.vu.nl)

																     SCREENDUMP(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)