Dual Monitor Settings

Set external monitor as the primary monitor
xrandr --output VGA1 --primary
xrandr --output VGA1 --auto --pos 0x0 --output LVDS1 --auto --below VGA1
after that use the monitor settings to adjust position

going back to laptop screen only
xrandr --output VGA1 --off --output LVDS1 --auto

Given that I'm using a laptop and my laptop screen identified as LVDS1 and the external monitor as VGA1, I set up three icons that run a script, to switch between clone, dual with LVDS1 as primary, and dual with VGA1 as primary.

Using the text editor Kate I created three files with the names:
VGA1-Primary.sh
LVDS1-Primary.sh
Clone-Monitors.sh

The text contents of VGA1-Primary.sh are:
xrandr --output VGA1 --right-of LVDS1
xrandr --output VGA1 --primary


The text contents of LVDS1-Primary.sh are:
xrandr --output LVDS1 --left-of VGA1
xrandr --output LVDS1 --primary


The text contents of Clone-Monitors.sh are:
xrandr --output LVDS1 --auto --output VGA1 --auto --same-as LVDS1

enable disable touchpad

Method #1
xinput list gets the name of the touchpad... for me it's "PS/2 Generic Mouse"

then white this shell script on desktop
#!/bin/sh
DEVICE="PS/2 Generic Mouse"
if [ `xinput list-props "$DEVICE" |awk '/Device Enabled/ { print $4}'` -eq 0 ]; then
xinput --set-prop "$DEVICE" "Device Enabled" 1
else
xinput --set-prop "$DEVICE" "Device Enabled" 0
fi

Method #2
disable: modprobe -r psmouse
enable: modprobe psmouse

GREP tips

* find lines beginning with
grep ^string

* exclude lines with characters
grep -Ev '{|}'

System Memory Size in Boot Parameters

use mem=XXK

Enable/Disable CPUs in Linux

cd /sys/devices/system/cpu

ls -l ... shows cpus
grep processor /proc/cpuinfo

echo 0 > cpuN/online ... disables that cpu
echo 1 > cpuN/online ... enables that cpu

or

use kernel boot parameters maxcpus=XX

Important Linux Tools for Monitoring

blktrace
oprofile (link)
powertop
perf

compile kernel with broken make-kpkg

apt-get install fakeroot build-essential crash kexec-tools makedumpfile kernel-wedge
apt-get build-dep linux
apt-get install git-core libncurses5 libncurses5-dev libelf-dev asciidoc binutils-dev

export CONCURRENCY_LEVEL=ncpu+1
make menuconfig
make-kpkg --initrd --append-to-version=**** kernel-image kernel-headers
... this will fail ...

make -j (ncpu+1)
make modules
make modules_install
make install

cd /boot
mkinitramfs -o initrd.img-2.6.25 2.6.25

# update-grub
use startup manager
apt-get install startupmanager

# vi /boot/grub/menu.lst
title Debian GNU/Linux, kernel 2.6.25 Default
root (hd0,0)
kernel /boot/vmlinuz root=/dev/hdb1 ro
initrd /boot/initrd.img-2.6.25
savedefault
boot