linux crontab yum安装
crontab工具来做计划任务，定时任务，执行某个脚本等等
1.检查是否已安装crontab
# crontab -bash: crontab: command not found
执行 crontab 命令如果报 command not found，表明没有安装.
2.yum安装
#yum -y install vixie-cron
1 Loaded plugins: security 2 base | 3.7 kB 00:00 3 epel | 4.7 kB 00:00 4 epel/primary_db | 6.0 MB 00:00 5 extras | 3.4 kB 00:00 6 extras/primary_db | 29 kB 00:00 7 updates | 3.4 kB 00:00 8 updates/primary_db | 5.3 MB 00:00 9 Setting up Install Process 10 Resolving Dependencies 11 --> Running transaction check 12 ---> Package cronie.x86_64 0:1.4.4-16.el6_8.2 will be installed 13 --> Processing Dependency: dailyjobs for package: cronie-1.4.4-16.el6_8.2.x86_64 14 --> Processing Dependency: /usr/sbin/sendmail for package: cronie-1.4.4-16.el6_8.2.x86_64 15 --> Running transaction check 16 ---> Package cronie-anacron.x86_64 0:1.4.4-16.el6_8.2 will be installed 17 --> Processing Dependency: crontabs for package: cronie-anacron-1.4.4-16.el6_8.2.x86_64 18 ---> Package exim.x86_64 0:4.89-2.el6 will be installed 19 --> Running transaction check 20 ---> Package crontabs.noarch 0:1.10-33.el6 will be installed 21 --> Finished Dependency Resolution 22 23 Dependencies Resolved 24 25 =============================================================================================================================================================================================== 26 Package Arch Version Repository Size 27 =============================================================================================================================================================================================== 28 Installing: 29 cronie x86_64 1.4.4-16.el6_8.2 base 75 k 30 Installing for dependencies: 31 cronie-anacron x86_64 1.4.4-16.el6_8.2 base 31 k 32 crontabs noarch 1.10-33.el6 base 10 k 33 exim x86_64 4.89-2.el6 epel 1.4 M 34 35 Transaction Summary 36 =============================================================================================================================================================================================== 37 Install 4 Package(s) 38 39 Total download size: 1.5 M 40 Installed size: 4.3 M 41 Downloading Packages: 42 (1/4): cronie-1.4.4-16.el6_8.2.x86_64.rpm | 75 kB 00:00 43 (2/4): cronie-anacron-1.4.4-16.el6_8.2.x86_64.rpm | 31 kB 00:00 44 (3/4): crontabs-1.10-33.el6.noarch.rpm | 10 kB 00:00 45 (4/4): exim-4.89-2.el6.x86_64.rpm | 1.4 MB 00:00 46 ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- 47 Total 10 MB/s | 1.5 MB 00:00 48 Running rpm_check_debug 49 Running Transaction Test 50 Transaction Test Succeeded 51 Running Transaction 52 Installing : exim-4.89-2.el6.x86_64 1/4 53 Installing : cronie-1.4.4-16.el6_8.2.x86_64 2/4 54 Installing : crontabs-1.10-33.el6.noarch 3/4 55 Installing : cronie-anacron-1.4.4-16.el6_8.2.x86_64 4/4 56 Verifying : crontabs-1.10-33.el6.noarch 1/4 57 Verifying : cronie-anacron-1.4.4-16.el6_8.2.x86_64 2/4 58 Verifying : exim-4.89-2.el6.x86_64 3/4 59 Verifying : cronie-1.4.4-16.el6_8.2.x86_64 4/4 60 61 Installed: 62 cronie.x86_64 0:1.4.4-16.el6_8.2 63 64 Dependency Installed: 65 cronie-anacron.x86_64 0:1.4.4-16.el6_8.2 crontabs.noarch 0:1.10-33.el6 exim.x86_64 0:4.89-2.el6 66 67 Complete!
安装完成后，可使用 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
crontab服务状态操作：
/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
添加到开机服务
在/etc/rc.d/rc.local这个脚本的末尾加上:
/sbin/service crond start
Loaded plugins: securitybase | 3.7 kB 00:00 epel | 4.7 kB 00:00 epel/primary_db | 6.0 MB 00:00 extras | 3.4 kB 00:00 extras/primary_db | 29 kB 00:00 updates | 3.4 kB 00:00 updates/primary_db | 5.3 MB 00:00 Setting up Install ProcessResolving Dependencies–> Running transaction check—> Package cronie.x86_64 0:1.4.4-16.el6_8.2 will be installed–> Processing Dependency: dailyjobs for package: cronie-1.4.4-16.el6_8.2.x86_64–> Processing Dependency: /usr/sbin/sendmail for package: cronie-1.4.4-16.el6_8.2.x86_64–> Running transaction check—> Package cronie-anacron.x86_64 0:1.4.4-16.el6_8.2 will be installed–> Processing Dependency: crontabs for package: cronie-anacron-1.4.4-16.el6_8.2.x86_64—> Package exim.x86_64 0:4.89-2.el6 will be installed–> Running transaction check—> Package crontabs.noarch 0:1.10-33.el6 will be installed–> Finished Dependency Resolution
Dependencies Resolved
=============================================================================================================================================================================================== Package Arch Version Repository Size===============================================================================================================================================================================================Installing: cronie x86_64 1.4.4-16.el6_8.2 base 75 kInstalling for dependencies: cronie-anacron x86_64 1.4.4-16.el6_8.2 base 31 k crontabs noarch 1.10-33.el6 base 10 k exim x86_64 4.89-2.el6 epel 1.4 M
Transaction Summary===============================================================================================================================================================================================Install 4 Package(s)
Total download size: 1.5 MInstalled size: 4.3 MDownloading Packages:(1/4): cronie-1.4.4-16.el6_8.2.x86_64.rpm | 75 kB 00:00 (2/4): cronie-anacron-1.4.4-16.el6_8.2.x86_64.rpm | 31 kB 00:00 (3/4): crontabs-1.10-33.el6.noarch.rpm | 10 kB 00:00 (4/4): exim-4.89-2.el6.x86_64.rpm | 1.4 MB 00:00 ———————————————————————————————————————————————————————————————–Total 10 MB/s | 1.5 MB 00:00 Running rpm_check_debugRunning Transaction TestTransaction Test SucceededRunning Transaction Installing : exim-4.89-2.el6.x86_64 1/4 Installing : cronie-1.4.4-16.el6_8.2.x86_64 2/4 Installing : crontabs-1.10-33.el6.noarch 3/4 Installing : cronie-anacron-1.4.4-16.el6_8.2.x86_64 4/4 Verifying : crontabs-1.10-33.el6.noarch 1/4 Verifying : cronie-anacron-1.4.4-16.el6_8.2.x86_64 2/4 Verifying : exim-4.89-2.el6.x86_64 3/4 Verifying : cronie-1.4.4-16.el6_8.2.x86_64 4/4
Installed: cronie.x86_64 0:1.4.4-16.el6_8.2
Dependency Installed: cronie-anacron.x86_64 0:1.4.4-16.el6_8.2 crontabs.noarch 0:1.10-33.el6 exim.x86_64 0:4.89-2.el6
Complete!