If you want to build six pack abs do this routine 3 - 4 times a week with other compound movements, follow a healthy diet and you will get them. (abmachinesguide.com)
Variations include Body Weight Squats, Dumbbell Squats, Barbell Squats, and many other compound movements. (popworkouts.com)
This also allows an increased intra-abdominal pressure from the core musculature, which will help you with the other compound movements. (fitnessandpower.com)