shell脚本对代码执行时间的计时

#!/bin/bash

# ccache is from epel mirrors:http://mirrors./epel/7Server/x86_64/

start_time=$(date +%s)

sleep 1

#sudo mock -r xxxx-v5.05-x86_64 --rebuild kernel-3.10.0-957.1.3.el7.xxxx.gd2389d1.src.rpm --no-clean --no-cleanup-after

end_time=$(date +%s)

cost_time=$[ $end_time-$start_time ]

echo "build kernel time is $(($cost_time/60))min $(($cost_time%60))s"