CentOS下使用yum命令安装计划任务程序crontab的方法

 更新时间:2017年09月05日 11:50:41   作者:微wx笑   我要评论
这篇文章主要介绍了CentOS下使用yum命令安装计划任务程序crontab的相关资料,需要的朋友可以参考下

 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、金沙国际官网、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澳门金沙网上娱乐网站的支持!

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