Here is a shell / Bash script that calculates Pi to 1000 digits:
bc -l <<< 'scale=1000; 4*a(1)' # which is shorter than the equivalent echo "scale=1000;4*a(1)" | bc -l
One more calculation using
bc: the golden ratio to 10 digits:
bc -l <<< 'scale=10;(1 + sqrt(5))/2'
- If you want a multi-threaded program (to test the performace of your machine?!) calculating pi, try y-cruncher