How to Safely Clean Pacman Package Cache in CachyOS and Arch Linux

✨ Quick Answer

In CachyOS and Arch Linux environments, the Pacman package manager never automatically purges downloaded .pkg.tar.zst archive binaries from /var/cache/pacman/pkg/. Over time, this directory routinely swells to 20GB-50GB, triggering low storage warnings on root partitions.

Quick Diagnostics

Cause

/var/lib/pacman and /var/cache/pacman/pkg directories accumulating dozens of package revisions

Solution

Prune obsolete package tarballs while retaining the latest 2 versions via sudo paccache -r

Cause

AUR build cache bloating user directories (~/.cache/yay or ~/.cache/paru)

Solution

Clean AUR cache using yay -Sc --aur or purge ~/.cache/yay

In CachyOS and Arch Linux environments, the Pacman package manager never automatically purges downloaded .pkg.tar.zst archive binaries from /var/cache/pacman/pkg/. Over time, this directory routinely swells to 20GB-50GB, triggering low storage warnings on root partitions.

Step-by-Step Solution

1. 1

   Step 1: Measure Current Pacman Cache Footprint

   Evaluate exact disk utilization:

   BASH Copy

   # Inspect storage footprint of the Pacman cache
   du -sh /var/cache/pacman/pkg/
   

2. 2

   Step 2: Prune Obsolete Versions Safely Using paccache

   The official paccache utility (from pacman-contrib) clears obsolete revisions while preserving safety rollbacks:

   BASH Copy

   # 1. Ensure pacman-contrib is installed
   sudo pacman -S pacman-contrib --noconfirm
   
   # 2. Retain only the 2 most recent package versions
   sudo paccache -r -k 2
   
   # 3. Purge cached files for uninstalled packages
   sudo paccache -ruk0
   

3. 3

   Step 3: Comprehensive Cache Flush (For Emergency Space Reclamation)

   When immediate disk recovery is mandatory:

   BASH Copy

   # Purge uninstalled package archives
   sudo pacman -Sc --noconfirm
   
   # Purge ALL cached archives completely
   sudo pacman -Scc --noconfirm
   

4. 4

   Step 4: Clear AUR Build Repositories (Yay / Paru)

   AUR helpers compile binaries inside user home directories:

   BASH Copy

   # If using Yay:
   yay -Sc --aur --noconfirm
   rm -rf ~/.cache/yay/*
   
   # If using Paru:
   paru -Scc --noconfirm
   

❓ Frequently Asked Questions (FAQ)

Why does Pacman retain all downloaded tarballs?

To allow instant offline package downgrades (pacman -U /var/cache/pacman/pkg/pkgname-old.pkg.tar.zst) if an upstream package update introduces regressions.

Is paccache.timer safe for production machines?

Yes. The service runs weekly in the background, keeping the 3 most recent package versions intact for stability.