MinIO 客户端命令 mc retention 用来为对象设置保留时间，语法如下：
C:\> mc retention -h
NAME:
mc retention - set retention for object(s)
USAGE:
mc retention COMMAND [COMMAND FLAGS | -h] [ARGUMENTS...]
COMMANDS:
set set retention for object(s)
clear clear retention for object(s)
info show retention for object(s)
help, h Shows a list of commands or help for one command
FLAGS:
--config-dir value, -C value path to configuration folder (default: "C:\\Users\\Administrator\\mc")
--quiet, -q disable progress bar display
--no-color disable color theme
--json enable JSON lines formatted output
--debug enable debug output
--insecure disable SSL certificate verification
--help, -h show help
