root@li226-15:~# ./
crontab.shmi h d m w user command
*/20 * * * * smmsp test -x /etc/init.d/sendmail && /usr/share/sendmail/sendmail cron-msp
09,39 * * * * root [ -x /usr/lib/php5/maxlifetime ] && [ -d /var/lib/php5 ] && find /var/lib/php5/ -type f -cmin +$(/usr/lib/php5/maxlifetime) -print0 | xargs -n 200 -r -0 rm
25 6 * * * root /etc/cron.daily/apt
25 6 * * * root /etc/cron.daily/bsdmainutils
25 6 * * * root /etc/cron.daily/dpkg
25 6 * * * root /etc/cron.daily/logrotate
25 6 * * * root /etc/cron.daily/man-db
25 6 * * * root /etc/cron.daily/ntp
25 6 * * * root /etc/cron.daily/popularity-contest
25 6 * * * root /etc/cron.daily/sendmail
25 6 * * * root /etc/cron.daily/standard
47 6 * * 7 root /etc/cron.weekly/man-db
找到一个程序,发现有这么些crontab