CentOS下使用yum命令安装计划任务程序crontab的方法

细雨如烟不染衣

 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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1 2	# crontab -bash: crontab: command not found

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...

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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1	#rm -f /var/run/yum.pid

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!

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)

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

或者使用

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# service crond start # service crond stop # service crond restart # service crond reload # service crond status

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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1	/sbin/service crond start

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