bash 圆周率计算

#!/bin/bash

CONCURRENCY=8
TIME_START=`date`
for ((idx = 0; idx < $CONCURRENCY; idx++))
do
time echo "scale=5000; a(1)*4" | bc -l > /dev/null &
done

echo "$TIME_START Start"

RUNNING_PROCESS_NUM=1
while [ $RUNNING_PROCESS_NUM -gt 0 ]
do
printf ".";
sleep 1
RUNNING_PROCESS_NUM=$(ps ax | grep ' bc -l' | grep -v 'grep' | wc -l)
done

TIME_STOP=`date`

echo "$TIME_STOP Stop"