shell-crontab（定时调度）

crontab: usage error: unrecognized optionusage:crontab [-u user] filecrontab [ -u user ] [ -i ] { -e | -l | -r }(default operation is replace, per 1003.2)-e(edit user's crontab)-l(list user's crontab)-r(delete user's crontab)-i(prompt before deleting user's crontab)crontab -lcrontab -ecrontab filecrontab -r#00 06 * * * shutdown -r now