系统启动时间
who -b
system boot Dec 20 10:45
date -d "$(awk -F. '{print $1}' /proc/uptime) second ago" +"%Y-%m-%d %H:%M:%S"
2019-12-20 10:45:03
系统已运行时间
cat /proc/uptime| awk -F. '{run_days=$1 / 86400;run_hour=($1 % 86400)/3600;run_minute=($1 % 3600)/60;run_second=$1 % 60;printf("%dd %d:%d:%d\n",run_days,run_hour,run_minute,run_second)}'