We will explore wiring the Pololu Pushbutton Power Switch, programming the Arduino to shut off the power, and making the unit "power on" only.
The Pololu Pushbutton Power Switch comes in two versions - the SV version geared towards 4.5V-20V range, and the LV which specifies 2.5V-7.0V range. I will use a 9V battery for this demo, and thus the SV version of the power switch.
Webpage for the Pololu Pushbutton Power Switch
1 - Arduino (I am using an UNO R3 for this Demo)
2 - Solderless Breadboard
3 - Pololu Pushbutton Power Switch SV
4 - 9V battery and holder with power leads
5 - 2.1mm male power jack to plug directly into the Arduino
Step 1: Getting familiar with the Pololu Power Switch
It also sports 2 connectors for a momentary contact switch, allowing you to use the provided switch directly on the board, or solder your own leads for a switch (or switches) separate from the unit.