CentOS下使用yum命令安装计划任务程序crontab的方法
概述
利用“任务计划”,可以将任何脚本、程序或文档安排在某个最方便的时间运行。通俗的讲就是定时执行某个脚本、程序。
常见用途
定时关机
定时检查更新
定时对系统配置、数据库、日志进行备份
定时清理垃圾文件
检测是否已安装
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# crontab
- bash : crontab : command not found
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执行 crontab 命令如果报 command not found,就表明没有安装.
开始安装
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# yum -y install vixie-cron
Loaded plugins: fastestmirror, refresh-packagekit, security
Existing lock /var/run/yum .pid: another copy is running as pid 25960.
Another app is currently holding the yum lock; waiting for it to exit ...
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可能是系统自动升级正在运行,yum在锁定状态中。
可以通过强制关掉yum进程:
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#rm -f /var/run/yum.pid
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然后就可以使用yum了。
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# yum -y install vixie-cron
Loaded plugins: fastestmirror, refresh-packagekit, security
Determining fastest mirrors
* base: mirrors.btte.net
* extras: mirrors.sina.cn
* updates: mirrors.sina.cn
base | 3.7 kB 00:00
extras | 3.4 kB 00:00
extras /primary_db | 32 kB 00:00
updates | 3.4 kB 00:00
updates /primary_db | 1.9 MB 00:07
Setting up Install Process
Resolving Dependencies
--> Running transaction check
---> Package cronie.x86_64 0:1.4.4-15.el6 will be installed
--> Processing Dependency: dailyjobs for package: cronie-1.4.4-15.el6.x86_64
--> Processing Dependency: /usr/sbin/sendmail for package: cronie-1.4.4-15.el6.x86_64
--> Running transaction check
---> Package cronie-anacron.x86_64 0:1.4.4-15.el6 will be installed
--> Processing Dependency: crontabs for package: cronie-anacron-1.4.4-15.el6.x86_64
---> Package sendmail.x86_64 0:8.14.4-9.el6 will be installed
--> Processing Dependency: procmail for package: sendmail-8.14.4-9.el6.x86_64
--> Running transaction check
---> Package crontabs.noarch 0:1.10-33.el6 will be installed
---> Package procmail.x86_64 0:3.22-25.1.el6_5.1 will be installed
--> Finished Dependency Resolution
Dependencies Resolved
===============================================================================================================================================================================================
Package Arch Version Repository Size
===============================================================================================================================================================================================
Installing:
cronie x86_64 1.4.4-15.el6 base 74 k
Installing for dependencies:
cronie-anacron x86_64 1.4.4-15.el6 base 31 k
crontabs noarch 1.10-33.el6 base 10 k
procmail x86_64 3.22-25.1.el6_5.1 base 162 k
sendmail x86_64 8.14.4-9.el6 base 716 k
Transaction Summary
===============================================================================================================================================================================================
Install 5 Package(s)
Total download size: 994 k
Installed size: 2.1 M
Downloading Packages:
(1 /5 ): cronie-1.4.4-15.el6.x86_64.rpm | 74 kB 00:00
(2 /5 ): cronie-anacron-1.4.4-15.el6.x86_64.rpm | 31 kB 00:00
(3 /5 ): crontabs-1.10-33.el6.noarch.rpm | 10 kB 00:00
(4 /5 ): procmail-3.22-25.1.el6_5.1.x86_64.rpm | 162 kB 00:00
(5 /5 ): sendmail-8.14.4-9.el6.x86_64.rpm | 716 kB 00:00
-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Total 1.3 MB /s | 994 kB 00:00
Running rpm_check_debug
Running Transaction Test
Transaction Test Succeeded
Running Transaction
Installing : procmail-3.22-25.1.el6_5.1.x86_64 1 /5
Installing : sendmail-8.14.4-9.el6.x86_64 2 /5
Installing : cronie-1.4.4-15.el6.x86_64 3 /5
Installing : crontabs-1.10-33.el6.noarch 4 /5
Installing : cronie-anacron-1.4.4-15.el6.x86_64 5 /5
ERROR:dbus.proxies:Introspect error on :1.2513: /org/freedesktop/PackageKit : dbus.exceptions.DBusException: org.freedesktop.DBus.Error.NoReply: Did not receive a reply. Possible causes include: the remote application did not send a reply, the message bus security policy blocked the reply, the reply timeout expired, or the network connection was broken.
Unable to send message to PackageKit
Verifying : crontabs-1.10-33.el6.noarch 1 /5
Verifying : cronie-anacron-1.4.4-15.el6.x86_64 2 /5
Verifying : sendmail-8.14.4-9.el6.x86_64 3 /5
Verifying : cronie-1.4.4-15.el6.x86_64 4 /5
Verifying : procmail-3.22-25.1.el6_5.1.x86_64 5 /5
Installed:
cronie.x86_64 0:1.4.4
15.el6
Dependency Installed:
cronie-anacron.x86_64 0:1.4.4-15.el6 crontabs.noarch 0:1.10-33.el6 procmail.x86_64 0:3.22-25.1.el6_5.1 sendmail.x86_64 0:8.14.4-9.el6
Complete!
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查看命令帮助
crontab 并不支持-h或–help之类的选项,不过还是可以通过它查看命令帮助
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# crontab -h
crontab :无效选项 -- h
crontab : usage error: unrecognized option
usage: crontab [-u user] file
crontab [-u user] [ -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 )
-s (selinux context)
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也可以使用 info crontab 命令查看详细的帮助信息。
cron服务提供crontab命令来设定cron服务的,以下是这个命令的一些参数与说明:
crontab -u //设定某个用户的cron服务,一般root用户在执行这个命令的时候需要此参数
crontab -l //列出某个用户cron服务的详细内容
crontab -r //删除没个用户的cron服务
crontab -e //编辑某个用户的cron服务
比如说root查看自己的cron设置:crontab -u root -l
再例如,root想删除fred的cron设置:crontab -u fred -r
在编辑cron服务时,编辑的内容有一些格式和约定,输入:crontab -u root -e
进入vi编辑模式,编辑的内容一定要符合下面的格式:/1 * * * ls >> /tmp/ls.txt
服务状态控制
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/sbin/service crond start // 启动服务
/sbin/service crond stop // 关闭服务
/sbin/service crond restart // 重启服务
/sbin/service crond reload // 重新载入配置
/sbin/service crond status // 查看状态
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或者使用
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# service crond start
# service crond stop
# service crond restart
# service crond reload
# service crond status
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开机启动
你也可以将这个服务在系统启动的时候自动启动:
在/etc/rc.d/rc.local这个脚本的末尾加上:
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/sbin/service crond start
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现在Cron这个服务已经在进程里面了,我们就可以用这个服务了。
总结
以上所述是小编给大家介绍的CentOS下使用yum命令安装计划任务程序crontab,希望对大家有所帮助,如果大家有任何疑问请给我留言,小编会及时回复大家的。在此也非常感谢大家对服务器之家网站的支持!
原文链接:http://blog.csdn.net/testcs_dn/article/details/48780971
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