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

# 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

# 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:

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

然后就可以使用yum了。

# 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

# 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

/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

# 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:

/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网站的支持!

以上是 CentOS下使用yum命令安装计划任务程序crontab的方法 的全部内容, 来源链接: utcz.com/z/356331.html

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