# yum -y install yum-downloadonly

# yum install --downloadonly nginx
Loaded plugins: downloadonly, fastestmirror
Loading mirror speeds from cached hostfile
 * base: mirror.fairway.ne.jp
 * epel: ftp.kddilabs.jp
 * extras: mirror.fairway.ne.jp
 * rpmforge: mirror.fairway.ne.jp
 * updates: centos.tt.co.kr
Setting up Install Process
Resolving Dependencies
--> Running transaction check
---> Package nginx.x86_64 0:1.4.1-1.el6.ngx will be installed
--> Finished Dependency Resolution

Dependencies Resolved

==================================================================================================================
 Package                 Arch                     Version                           Repository               Size
==================================================================================================================
Installing:
 nginx                   x86_64                   1.4.1-1.el6.ngx                   nginx                   311 k

Transaction Summary
==================================================================================================================
Install       1 Package(s)

Total download size: 311 k
Installed size: 770 k
Is this ok [y/N]: y
Downloading Packages:
nginx-1.4.1-1.el6.ngx.x86_64.rpm                                                           | 311 kB     00:01     


exiting because --downloadonly specified 

# find / -name "nginx-1.4.1-1.el6.ngx.x86_64.rpm"
/var/cache/yum/x86_64/6/nginx/packages/nginx-1.4.1-1.el6.ngx.x86_64.rpm

# ll /var/cache/yum/base/packages
# ll /var/cache/yum/epel/packages
# ll /var/cache/yum/remi/packages