Linux centos7安装Jenkins( jenkins-2.227-1.1.noarch.rpm)时遇到问题：
1. 出现问题1：安装jenkins一直失败，提示No such file or directory
[helen@linuxprobe Jenkins]$ sudo rpm -ivh jenkins-2.227-1.1.noarch.rpm
Preparing... ################################# [100%]
stat: cannot stat ‘/var/cache/jenkins’: No such file or directory
stat: cannot stat ‘/var/log/jenkins’: No such file or directory
stat: cannot stat ‘/var/lib/jenkins’: No such file or directory
error: %pre(jenkins-2.227-1.1.noarch) scriptlet failed, exit status 1
error: jenkins-2.227-1.1.noarch: install failed
-->原因：之前已经有了/etc/sysconfig/jenkins
解决方法：
进入/etc/sysconfig，删除掉jenkins，重新安装.
rm -rf jenkins
备注：sudo是因为不是root用户，无权限，所以使用sudo
如果是root用户，则不需要，直接rpm -ivh jenkins-2.227-1.1.noarch.rpm安装Jenkins，提示：stat: cannot stat ‘/var/cache/jenkins