The command `yum upgrade` is similar to `yum update`, but it goes a step further. While `yum update` only updates packages to their latest versions within the same major release, `yum upgrade` can also upgrade packages to a newer major release if available.
**Here's a breakdown of the key difference:**
**yum update:**
* Updates packages to the latest minor versions or bug fix releases within the same major release.
* Generally safer and less likely to cause compatibility issues.
**yum upgrade:**
* Updates packages to the latest available version, which may include major release upgrades.
* Can introduce significant changes and potential compatibility issues with other software.
* More suitable when you want to stay on the cutting edge or need features from a newer major release.
**Other aspects of `yum upgrade` are similar to `yum update`:**
**Checks for updates:** Connects to repositories and checks for newer versions of installed packages.
**Lists updates:** Displays a list of packages that will be upgraded and the version changes.
**Prompts for confirmation:** Asks you to confirm before proceeding with the upgrades.
**Downloads and installs updates:** Downloads and installs the new packages, replacing the older ones.
**Resolves dependencies:** Handles dependencies to ensure required packages are also updated or installed.
**Requires root privileges:** Needs to be run with `sudo` or as root.
**Needs internet connection:** Requires an active internet connection to download updates.
**May require a reboot:** May prompt for a reboot after upgrading critical packages.
**Important:**
**Backup:** It's even more crucial to back up your data before running `yum upgrade` as major release upgrades can have a greater impact on your system.
**Caution:** Use `yum upgrade` with caution, especially in production environments, as it can introduce unforeseen issues.
**Testing:** If possible, test major upgrades in a non-production environment first to identify any compatibility problems.
**Remember:** Keeping your system up-to-date is important, but choose between `yum update` and `yum upgrade` based on your specific needs and risk tolerance.
**References:**