shell腳本計算時間差

#! /bin/bash

beginTime=$(date "+%Y-%m-%d %H:%M:%S")
echo "beginTime:" $beginTime

sleep 12

endTime=$(date "+%Y-%m-%d %H:%M:%S")
echo "endtime:" $endTime

duration=$(($(date +%s -d "${endTime}")-$(date +%s -d "${beginTime}")));
echo "時間差:" $duration"s"

其中

%s表示seconds since 1970-01-01 00:00:00 UTC
-d表示display time described by STRING, not 'now'

　　

執行演示：

# source a.sh
beginTime: 2022-01-20 19:19:30
endtime: 2022-01-20 19:19:42
時間差: 12s