keepcache=0 更改为1下载RPM包 不会自动删除
vi /etc/yum.conf
[main] cachedir=/var/cache/yum/$basearch/$releasever # 安装包默认下载地址 keepcache=1 # 不会自动删除 debuglevel=2 logfile=/var/log/yum.log exactarch=1 obsoletes=1 gpgcheck=1 plugins=1 installonly_limit=5 bugtracker_url=http://bugs.centos.org/set_project.php?project_id=23&ref=http://bugs.centos.org/bug_report_page.php?category=yum distroverpkg=centos-release
只下载安装包，不安装指令
yum install --downloadonly --downloaddir=/home/java java