概述
利用“任務計劃”，可以將任何腳本、程序或文檔安排在某個最方便的時間運行。通俗的講就是定時執行某個腳本、程序。
常見用途
定時關機
定時檢查更新
定時對系統配置、數據庫、日志進行備份
定時清理垃圾文件
檢測是否已安裝
# crontab-bash: crontab: command not found
執行 crontab 命令如果報 command not found，就表明沒有安裝.
開始安裝
# yum -y install vixie-cronLoaded plugins: fastestmirror, refresh-packagekit, securityExisting 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...
可能是系統自動升級正在運行，yum在鎖定狀態中。
可以通過強制關掉yum進程：
#rm -f /var/run/yum.pid
然后就可以使用yum了。
# yum -y install vixie-cronLoaded plugins: fastestmirror, refresh-packagekit, securityDetermining fastest mirrors * base: mirrors.btte.net * extras: mirrors.sina.cn * updates: mirrors.sina.cnbase | 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 ProcessResolving 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 ResolutionDependencies Resolved=============================================================================================================================================================================================== Package Arch Version Repository Size===============================================================================================================================================================================================Installing: cronie x86_64 1.4.4-15.el6 base 74 kInstalling 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 kTransaction Summary===============================================================================================================================================================================================Install 5 Package(s)Total download size: 994 kInstalled size: 2.1 MDownloading 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_debugRunning Transaction TestTransaction Test SucceededRunning 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 0:1.4.415.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!
查看命令幫助
crontab 并不支持-h或 主站蜘蛛池模板： 无锡市| 平罗县| 潮州市| 安塞县| 永胜县| 虹口区| 南部县| 永和县| 辰溪县| 永丰县| 台湾省| 枞阳县| 彝良县| 沅江市| 南部县| 丽水市| 石狮市| 遂平县| 柳州市| 洛阳市| 和龙市| 甘孜| 南雄市| 阜南县| 贡嘎县| 彭泽县| 丁青县| 福安市| 南召县| 商洛市| 定兴县| 大丰市| 光泽县| 宁德市| 会理县| 陆丰市| 同德县| 基隆市| 大洼县| 甘孜县| 铜川市|