jenkins centos6.5 官方安装具体步骤及碰到问题、解决办法：
1.映射源：sudo wget -O /etc/yum.repos.d/jenkins.repo https://pkg.jenkins.io/redhat-stable/jenkins.repo报错如下：ERROR: cannot verify pkg.jenkins.io’s certificate, issued by “/C=US/O=Let’s Encrypt/CN=R3”:
Issued certificate has expired.To connect to pkg.jenkins.io insecurely, use ‘–no-check-certificate’.
解决办法如下命令：
sudo wget --no-check-certificate -O /etc/yum.repos.d/jenkins.repo https://pkg.jenkins.io/redhat-stable/jenkins.repo
2.导入密钥：
sudo rpm --import https://pkg.jenkins.io/redhat-stable/jenkins.io.key
3.安装yum install epel-release # repository that provides 'daemonize’报错：No package epel-release available.Error: Nothing to do， 解决办法下载centos 6.5 第三方资源库epal 版本：
wget https://archives.fedoraproject.org/pub/archive/epel/6/x86_64/epel-release-6-8.noarch.rpm
4.安装：
rpm -ivh epel-release-6-8.noarch.rpm
5.epel-release获取最新，安装daemonize
yum install epel-release # repository that provides 'daemonize'
6.jenkins安装
yum install jenkins
7.jenkins启动报错：systemctl start jenkinsbash: systemctl: command not found，解决办法如下：
service jenkins start
8.jenkins启动报错：service jenkins start
Starting Jenkins File “/usr/bin/java” is not executable. 解决办法修改本地java环境路径
cat /etc/rc.d/init.d/jenkins
/usr/lib/jvm/java-11-openjdk-amd64 ----> /usr/local/jdk8/bin/java
9.jenkins 安装成功，正常启动
service jenkins start