問題：執行安裝FTP時，報出

** Found 1 pre-existing rpmdb problem(s), 'yum check' output follows:
wget-1.12-5.el6_6.1.x86_64 is a duplicate with wget-1.12-1.8.el6.x86_64

的錯誤資訊。原因為系統中存在兩個版本的wget，產生兩個wget版本的原因可能是yum源更新的問題。所以這時想到的辦法就是重置yum源和更新yum源

執行過程如下：

[[email protected] ~]# yum install vsftpd
Loaded plugins: fastestmirror, refresh-packagekit, security
Loading mirror speeds from cached hostfile
 * atomic: mirrors.hosting.in.th
 

Setting up Install Process
Resolving Dependencies
There are unfinished transactions remaining. You might consider running yum-complete-transaction first to finish them.
--> Running transaction check
---> Package vsftpd.x86_64 0:2.2.2-14.el6 will be installed
--> Finished Dependency Resolution

 
Dependencies Resolved

=========================================================================================
 Package        Arch           Version                Repository                    Size
=========================================================================================
Installing:
 vsftpd         x86_64         2.2.2-14.el6           CentOS.6.base.x86_64         152 k
 


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

Total download size: 152 k
Installed size: 332 k
Is this ok [y/N]: y
Downloading Packages:
vsftpd-2.2.2-14.el6.x86_64.rpm                                    | 152 kB     00:00     
Running rpm_check_debug
Running Transaction Test
Transaction Test Succeeded
Running Transaction
** Found 1 pre-existing rpmdb problem(s), 'yum check' output follows:
wget-1.12-5.el6_6.1.x86_64 is a duplicate with wget-1.12-1.8.el6.x86_64

解決辦法：

wget http://www.atomicorp.com/installers/atomic

 sh ./atomic

執行到這裡時報錯如下：

Installing the Atomic GPG keys: OK

Downloading atomic-release-1.0-21.el6.art.noarch.rpm: warning: waiting for transaction lock on /var/lib/rpm/.rpm.lock

解決辦法：刪除/var/lib/rpm/.rpm.lock即可，之後重建正常。

 rm -f /var/lib/rpm/.rpm.lock
 rpm --rebuilddb

也可通過fuser /var/lib/rpm/.rpm.lock檢視佔用的程序，之後ps aux |grep processid找到對應程式，殺死即可。

[root@SZB-L0015013 ~]# yum check-update

更新完後就可以正常安裝了