Linux下面的任务部署大家都知道是利用crontab来实现的，至于crontab的一些类型我这里就不详细的来阐述，例如：
-e (edit user's crontab)--编辑当前的计划任务
-l (list user's crontab)--查看当前的计划任务
-r (delete user's crontab)--删除当前的计划任务
-ri (prompt before deleting user's crontab)--删除前给出确认,-r的话就是直接删除，通常使用下面的，-ri删除操作危险
king@ubuntu:/$ crontab -ri
crontab: really delete king's crontab? (y/n)
--提示你是否删除
格式：
大概的语法知道了，下面我们就从一个0起步的人做起，此时我们的系统里面的计划任务就是一个空白，没有设置任何计划任务，也可以创建一个新用户登录查看
step1:以study 用户登录执行crontab -l命令
study@ubuntu:/$ crontab -l
# Edit this file to introduce tasks to be run by cron.
#
# Each task to run has to be defined through a single line
# indicating with different fields when the task will be run
# and what command to run for the task
#
# To define the time you can provide concrete values for
# minute (m), hour (h), day of month (dom), month (mon),
# and day of week (dow) or use '*' in these fields (for 'any').#
# Notice that tasks will be started based on the cron's system
# daemon's notion of time and timezones.
#
# Output of the crontab jobs (including errors) is sent through
# email to the user the crontab file belongs to (unless redirected).
# For example, you can run a backup of all your user accounts
# at 5 a.m every week with:
# 0 5 * * 1 tar -zcf /var/backups/home.tgz /home/
#
# For more information see the manual pages of crontab(5) and cron(8)
#
# m h dom mon dow command
study@ubuntu:/$
可以看出最后面的不带#注释后面什么也没有，切换一个用计划任务的用户king,再次执行crontab -l
# Edit this file to introduce tasks to be run by cron.
#
# Each task to run has to be defined through a single line
# indicating with different fields when the task will be run
# and what command to run for the task
#
# To define the time you can provide concrete values for
# minute (m), hour (h), day of month (dom), month (mon),
# and day of week (dow) or use '*' in these fields (for 'any').#
# Notice that tasks will be started based on the cron's system
# daemon's notion of time and timezones.
#
# Output of the crontab jobs (including errors) is sent through
# email to the user the crontab file belongs to (unless redirected).
#
# For example, you can run a backup of all your user accounts
# at 5 a.m every week with:
# 0 5 * * 1 tar -zcf /var/backups/home.tgz /home/
#
# For more information see the manual pages of crontab(5) and cron(8)
#
# m h dom mon dow command
*/2 * * * * date >>/home/king/b1/time.txt
king@ubuntu:/$
大家可以清楚的看到这一行：*/2 * * * * date >>/home/king/b1/time.txt
这个就是一个每隔2分钟读取当前时间输出到/home/king/b1/time.txt这个文件中，下面我们切换回study用户
crontab -e
# Edit this file to introduce tasks to be run by cron.
#
# Each task to run has to be defined through a single line
# indicating with different fields when the task will be run
# and what command to run for the task
#
# To define the time you can provide concrete values for
# minute (m), hour (h), day of month (dom), month (mon),
# and day of week (dow) or use '*' in these fields (for 'any').#
# Notice that tasks will be started based on the cron's system
# daemon's notion of time and timezones.
#
# Output of the crontab jobs (including errors) is sent through
# email to the user the crontab file belongs to (unless redirected).
# For example, you can run a backup of all your user accounts
# at 5 a.m every week with:
# 0 5 * * 1 tar -zcf /var/backups/home.tgz /home/
#
# For more information see the manual pages of crontab(5) and cron(8)
#
# m h dom mon dow command
~
"/tmp/crontab.Aulssl/crontab" 22L, 886C
我们发现不能编辑，此时就要切换一下到编辑模式：i 进入编辑模式 输入
*/1 * * * * date >>/home/study/test/testdate.txt
然后按Esc退出编辑模式
然后按Shift+: 保存
然后按wq 退出
编辑成功 crontab -l 查看我们编辑的任务
# Edit this file to introduce tasks to be run by cron.
#
# Each task to run has to be defined through a single line
# indicating with different fields when the task will be run
# and what command to run for the task
#
# To define the time you can provide concrete values for
# minute (m), hour (h), day of month (dom), month (mon),
# and day of week (dow) or use '*' in these fields (for 'any').#
# Notice that tasks will be started based on the cron's system
# daemon's notion of time and timezones.
#
# Output of the crontab jobs (including errors) is sent through
# email to the user the crontab file belongs to (unless redirected).
# For example, you can run a backup of all your user accounts
# at 5 a.m every week with:
# 0 5 * * 1 tar -zcf /var/backups/home.tgz /home/
#
# For more information see the manual pages of crontab(5) and cron(8)
#
# m h dom mon dow command
*/1 * * * * date >>/home/study/test/testdate.txt
study@ubuntu:/$
OK 部署上去了，接着看部署执行效果 cd /home/study/test/
study@ubuntu:/$ cd /home/study/test
study@ubuntu:~/test$ cat testdate--这样写
cat: testdate: No such file or directory--提示不存在
study@ubuntu:~/test$ cat testdate.txt--cat 查看文件的全称 ok
Wed Mar 6 11:57:01 CST 2013
Wed Mar 6 11:58:02 CST 2013
Wed Mar 6 11:59:01 CST 2013
Wed Mar 6 12:00:01 CST 2013
Wed Mar 6 12:01:01 CST 2013
study@ubuntu:~/test$
最后要强调的是每一个crontab是针对当前用户的，用户king 有自己的计划任务 用户study也有自己的计划任务
可以看到 在文件夹里面已经按照每分钟输入格式显示出来了。以上文章献给初学者，共勉!