Calculate disk space consumed by the YUM or DNF package manager metadata and RPM cache.
DNF/yum caches two distinct things under /var/cache/dnf (or /var/cache/yum on older systems): repository metadata (the compressed package lists, dependency info and checksums each enabled repo publishes, needed to resolve `dnf install`/`search` without re-downloading metadata every time) and actual downloaded RPM package files (kept after install unless `keepcache=0`, useful for reinstalling or rolling back without re-downloading). `dnf clean all` removes both, recovering their combined size, at the cost of the next operation needing to re-download metadata (and packages, if reinstalled).
Cache size
cache_size = repos × packages_per_repo × metadata_per_package + cached_rpm_count × avg_rpm_size
`dnf clean metadata` removes only the cached repository metadata (forcing a fresh metadata download on the next operation), while `dnf clean all` also removes cached downloaded RPM packages — use `metadata` alone if you just want fresh package lists without losing cached RPMs for possible reinstalls.
Under /var/cache/dnf/, with a separate subdirectory per enabled repository containing both the repo's metadata (repodata/) and any downloaded packages/ subdirectory — `du -sh /var/cache/dnf/*` breaks down usage per repo.
No — clearing the cache only removes downloaded metadata and RPM files used during install/update operations; it has no effect on packages already installed on the system, since those live under the RPM database and filesystem, not the cache directory.