Yum is a repository centric package manager that installs RPM packages on Red Hat like operating systems. Yum resolves dependencies automatically. Yum also understands the concept of package groups, which are collections of software commonly installed together. Yum maintains a local list of software repositories.
- [Narrator] We've talked about the RPM command and the RPM package format already in this course. RPM knows what its dependencies are, and has the ability to download software from FTP and web servers. The thing that's missing is a repository-centric view. RPM does not manage software collections in remote repositories. As such, Yum was created by Yellowdog Linux, and has since been adopted by many Red Hat-based distributions including Fedora and CentOS. Yum resolves dependencies automatically. This means it downloads and installs all software packages necessary.
This includes packages that the user didn't specify, if the chosen package requires them. Yum has the concept of software package groups. A group is a list of software that is usually installed together. For instance, we could have a web server group that included the web server, and other tools commonly installed with it. Yum repositories contain RPM software packages. The Yum client maintains a local list of software repositories. Users can add repositories by just adding a new Yum configuration file for them.
The Yum client also maintains a local list of all available software. The package install process using Yum is pretty straightforward. First, the Yum client contacts the repositories that it's aware of, and gets their list of software packages. These lists are then cached locally, and it updates them during install operations. The user then selects a software package that they want to install. Users can select packages to install by using either CLI or GUI tools. Yum then calculates dependencies. This would be the requested software package, and any packages that it requires.
Yum then downloads all software packages and installs them using the RPM libraries, just like the RPM command does. Once the install has finished, Yum updates the RPM package database. Installing software using Yum couldn't be easier. Yum also has the concept of software groups. Yum groups contain multiple software packages. These software packages are usually installed together. All software in a group can be installed at once. All software in a group can be removed at once. Groups can contain optional software.
Option software is related software, but not installed by default. Groups make configuring a system quicker. Installing a group of software with one command is much easier than installing each package individually.
- List the factors that must be checked before downloading a Linux software package from the internet.
- Cite what must be done before installing software from source.
- State the key difference between a local package manager and a repository-based manager.
- Write what you would specify on the command line to change the rpm query format.
- Explain how a Yum client knows what software can be installed.
- Identify which directory Yum repository configure files are stored.