任务计划2

[root@localhost app]# cat /etc/crontab

SHELL=/bin/bash

PATH=/sbin:/bin:/usr/sbin:/usr/bin:/root/bin

MAILTO=root

# For details see man 4 crontabs

# Example of job definition:

# .—————- minute (0 – 59)

# | 
.————- hour (0 – 23)

# | 
|  .———- day of month (1 –
31)

# | 
|  |  .——- month (1 – 12) OR jan,feb,mar,apr
…

# | 
|  |  | 
.—- day of week (0 – 6) (Sunday=0 or 7) OR sun,mon,tue,wed,thu,fri,sat

# | 
|  |  |  |

 * 
*  *  *  *
root cron.sh

@reboot root touch /app/reboot.log

You have new mail in /var/spool/mail/root

[root@localhost ~]# cd  /etc/cron

cron.d/       cron.daily/   cron.deny    
cron.hourly/  cron.monthly/
crontab       cron.weekly/ 

[root@localhost ~]# cd  /etc/cron

cron.d/       cron.daily/   cron.deny    
cron.hourly/  cron.monthly/
crontab       cron.weekly/ 

[root@localhost ~]# 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]# which run-parts

/usr/bin/run-parts

[root@localhost cron.d]# rpm -qf  /usr/bin/run-parts

crontabs-1.10-33.el6.noarch

[root@localhost cron.d]#

[root@localhost cron.d]# ll /etc/cron

cron.d/       cron.daily/   cron.deny    
cron.hourly/  cron.monthly/
crontab       cron.weekly/ 

[root@localhost cron.d]# ll
/etc/cron.hourly/

total 4

-rwxr-xr-x. 1 root root 409 Nov 10  2015 0anacron

[root@localhost etc]# 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]# cat
/etc/cron.hourly/0anacron

#!/bin/bash

# Skip excecution unless the date has
changed from the previous run

if test -r /var/spool/anacron/cron.daily;
then

   
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

[root@localhost cron.d]# cd /etc/cron.d

cron.d/    
cron.daily/ cron.deny  

[root@localhost cron.d]# cd /etc/cron.daily/

[root@localhost cron.daily]# ls

cups 
logrotate  makewhatis.cron  mlocate.cron 
prelink  readahead.cron  tmpwatch

[root@localhost cron.daily]# whatis rm

rm                   (1p)  – remove directory entries

rm                   (1)  – remove files or directories

[root@localhost ~]# which crontab       //  普通用户定义计划任务需要借助这个工具实现

/usr/bin/crontab

You have new mail in /var/spool/mail/root

[root@localhost ~]# crontab -e -u fsy

* * * * * 
wall fsycron

[root@localhost cron]# cd /var/spool/cron/

[root@localhost cron]# ls

Fsy

[root@localhost cron.daily]# which crontab

/usr/bin/crontab

[root@localhost cron.daily]# ls  /usr/bin/crontab

/usr/bin/crontab

[root@localhost cron.daily]# ll  /usr/bin/crontab

-rwsr-xr-x. 1 root root 51784 Nov 10  2015 /usr/bin/crontab

[root@localhost cron]# crontab  -l                   // 查看计划任务

no crontab for root

[root@localhost cron]# export  EDITOR=vim

[root@localhost cron]# crontab -e -u fsy

[root@localhost cron]# crontab  -r           
// 删除所有的计划任务

[root@localhost cron]# ls /var/spool/cron/      // 相当于删除这个目录里的所有文件

Fsy

[root@localhost cron]# cat /var/log/cron

[root@localhost cron]# vim /etc/cron.deny

[root@localhost cron]# cat /etc/cron.deny

Fsy

[fsy@localhost app]$ crontab -e

You (fsy) are not allowed to use this
program (crontab)

See crontab(1) for more information

[root@localhost cron]# echo >
/etc/cron.deny

[root@localhost ~]# grep -E ‘^(S|M)’  /proc/meminfo

MemTotal:        1004140 kB

MemFree:          241724 kB

SwapCached:            0 kB

Mlocked:               0 kB

SwapTotal:       4095996 kB

SwapFree:        4095996 kB

Mapped:            56584 kB

Shmem:              2924 kB

Slab:             131392 kB

SReclaimable:      62108 kB

SUnreclaim:        69284 kB