Under the Linux system, the Yum command looks at which packages are installed:
$yum list installed//list all installed packages
Yum commands commonly used for package operations:
1. Find Packages using Yum
Command: Yum Search
2. List all packages that can be installed
Command: Yum list
3. List all the packages that can be updated
Command: Yum list updates
4. List all installed packages
Command: Yum List installed
5. List all packages that are installed but not within Yum Repository
Command: Yum list extras
6. List the specified packages
Command: Yum list
7. Use Yum to get package information
Command: Yum Info
8. Listing information for all packages
Command: Yum Info
9. List all updatable package information
Command: Yum info updates
10. List all installed package information
Command: Yum info installed
11. List all installed but not within Yum Repository package information
Command: Yum info extras
12. List which files the package provides
Command: Yum provides
How to use Yum to see which packages are installed under Linux
