cron 和anacron 、日志转储的周期任务

[root@localhost ~]# chkconfig --list | grep "cron"
crond              0:off    1:off    2:on    3:on    4:on    5:on    6:off

[root@localhost ~]# cd /etc/init.d
[root@localhost init.d]# ls
abrt-ccpp         certmonger  halt          mcelogd     nfs-rdma     quota_nld    rpcsvcgssd  sysstat
abrtd             cgconfig    ip6tables     mdmonitor   ntpd         rdisc        rsyslog     udev-post
abrt-oops         cgred       iptables      messagebus  ntpdate      rdma         sandbox     winbind
acpid             cpuspeed    irqbalance    netconsole  numad        restorecond  saslauthd   ypbind
atd               crond       kdump         netfs       oddjobd      rngd         single
auditd            cups        killall       network     portreserve  rpcbind      smartd
autofs            functions   lvm2-lvmetad  nfs         postfix      rpcgssd      sshd
blk-availability  haldaemon   lvm2-monitor  nfslock     psacct       rpcidmapd    sssd

[root@localhost init.d]# cd /etc/cron.d
[root@localhost cron.d]# ls
0hourly  raid-check  sysstat
[root@localhost cron.d]# cat 0hourly 
SHELL=/bin/bash
PATH=/sbin:/bin:/usr/sbin:/usr/bin
MAILTO=root
HOME=/
01 * * * * root run-parts /etc/cron.hourly

[root@localhost cron.d]# cd  /etc/cron.hourly/
[root@localhost cron.hourly]# ls
0anacron  mcelog.cron
[root@localhost cron.hourly]# cat 0anacron 
#!/bin/bash
# Skip excecution unless the date has changed from the previous run 
if test -r /var/spool/anacron/cron.daily; then
/var/spool/anacron/cron.daily文件中 存放cron 上次启动时间
如果当期的时间和文件中的时间一致，表示本次已经执行完毕，无需再次执行
 day=`cat /var/spool/anacron/cron.daily`
fi
if [ `date +%Y%m%d` = "$day" ]; then
 exit 0;
fi
 
# Skip excecution unless AC powered
if test -x /usr/bin/on_ac_power; then
 /usr/bin/on_ac_power &> /dev/null
 if test $? -eq 1; then
 exit 0
 fi
fi
/usr/sbin/anacron -s 开机后的第一个 一分钟 （每个小时的第一分钟）开启 anacron 服务
anacron 由 cron 启动

[root@localhost cron]# cat /etc/anacrontab 
# /etc/anacrontab: configuration file for anacron
anacron的配置文件
# See anacron(8) and anacrontab(5) for details.
 
SHELL=/bin/sh
PATH=/sbin:/bin:/usr/sbin:/usr/bin
MAILTO=root
# the maximal random delay added to the base delay of the jobs
RANDOM_DELAY=45 随机延迟时间 0-45 分钟
# the jobs will be started during the following hours only
START_HOURS_RANGE=3-22 执行时间 3点到 22点
几天执行一次 固定延迟几分钟 nice 执行的命令
#period in days delay in minutes job-identifier command
1 5 cron.daily nice run-parts /etc/cron.daily
7 25 cron.weekly nice run-parts /etc/cron.weekly
@monthly 45 cron.monthly nice run-parts /etc/cron.monthly

[root@localhost cron.daily]# cat logrotate 
#!/bin/sh
/usr/sbin/logrotate /etc/logrotate.conf 执行logrotate 转储命令，读 
取/etc/logrotate.conf 主要配置文件（包含次要配置文件/etc/logrotate.d）按照 配置文
件的规则对日志进行转储
EXITVALUE=$?
if [ $EXITVALUE != 0 ]; then
 /usr/bin/logger -t logrotate "ALERT exited abnormally with [$EXITVALUE]"
fi
exit 0