cat /dev/random | rngtest -c 10000
rngtest -c 1000 </dev/random
 
dd if=/dev/random of=/dev/null bs=1024 count=1 iflag=fullblock
 
pv /dev/random>/dev/null
 
ls /proc/sys/kernel/random/*; for i in {1..100}; do sleep 10; cat /proc/sys/kernel/random/entropy_avail; done