This guide walks through fixing yum/rpm failures during package installation (e.g., vsftpd) caused by unfinished transactions, duplicate packages, or a stuck RPM database lock.

Symptom

Attempting too install vsftpd fails with messages about unfinished transactions and duplicate packages:

$ sudo yum install vsftpd
Loaded plugins: fastestmirror, refresh-packagekit, security
Loading mirror speeds from cached hostfile
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)

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

Common causes:

• Mutliple versions of the same package installed (duplicate RPMs)
• A previous yum/rpm run left the data base locked
• Repository metadata issues

Step 1: Complete or clean up unfinished transactions

If yum hints at unfinished work, finish or clean it up.

# Install yum-utils if needed
sudo yum install -y yum-utils

# Try to finish pending transactions
sudo yum-complete-transaction

# Or clean them up explicitly
sudo yum-complete-transaction --cleanup-only

Check yum history if issues persist:

sudo yum history
sudo yum history info last

Step 2: Remove duplicate packages

Identify duplicates and remove the older variants.

# List duplicates
sudo package-cleanup --dupes

# Attempt automatic cleanup of duplicates
sudo package-cleanup --cleandupes

# Or handle a specific package manually (example for wget)
rpm -qa | grep '^wget-'
sudo yum remove wget-1.12-1.8.el6.x86_64

Step 3: Refresh or reset repositories (example: Atomic repo)

If you need to reset/augment repositories (as with Atomic), run the installer. You may use curl or wget:

# Using curl
curl -fsSLO https://www.atomicorp.com/installers/atomic
sudo sh ./atomic

Or:

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

If the instalelr hangs with a lock warning like below, continue to Step 4.

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

Step 4: Resolve the RPM database lock

First, determine whether another process legitimately holds the lock.

# See which process has the lock
sudo fuser -v /var/lib/rpm/.rpm.lock

# Inspect and stop it if appropriate
ps -fp <PID>
sudo kill -TERM <PID>
# As a last resort
sudo kill -9 <PID>

If no process is using the lock (stale lock), remove it and rebuild the RPM database.

# Remove lock and Berkeley DB environment files (if present)
sudo rm -f /var/lib/rpm/.rpm.lock
sudo rm -f /var/lib/rpm/__db*

# Rebuild the RPM database
sudo rpm --rebuilddb

Step 5: Clean metadata and refresh package lists

sudo yum clean all
sudo yum makecache
sudo yum check-update

Step 6: Retry the installation

sudo yum install -y vsftpd

If you still encounter problems, verify the RPM database and run a basic health check:

sudo yum check
sudo rpm -Va