Pacman -Sy Behavior: Installing New Packages After Sync Without Full Upgrade

Answer to the Core Question

Pacman performs dependency checks against the database snapshot that was created by the most recent pacman -Sy. It does not fall back to the pre‑sync state. After a sync, the package database is considered up‑to‑date, and any new package you install will be resolved against that metadata.

What this means for you

• Installing pacman -S pkg immediately after a sync will use the latest available versions of all dependencies.
• If the new package requires a newer version of a library that you have not yet upgraded, pacman will still install the required dependency from the sync database.
• Only a subsequent full upgrade (pacman -Syu) will bring the rest of the system to the newest state.

Recommended Command Sequence

1. sudo pacman -Sy – update the local package database.
2. sudo pacman -S newpkg – install the desired package.
3. sudo pacman -Syu – upgrade the system to ensure all packages are on compatible, latest versions.

Running pacman -Syu immediately after adding a package is the safest way to avoid a half‑upgraded system and potential dependency conflicts.

Using IgnorePkg

Adding a package to IgnorePkg in /etc/pacman.conf tells pacman to skip that package during upgrades. This can be useful for:

• Holding a kernel or driver that is incompatible with a newer kernel.
• Keeping a custom‑built library that you don’t want replaced.

However, be aware that:

• If the ignored package is a dependency of a newer package you install later, pacman will report a conflict during the next pacman -Syu.
• Repeatedly ignoring packages can eventually lead to a broken dependency graph.

When using IgnorePkg, always run pacman -Syu and watch for “dependency conflict” messages. If a conflict appears, you may need to upgrade the ignored package manually or adjust the ignore list.

Verification Checklist

# 1. Sync the database and note the timestamp
pacman -Sy
ls -l /var/lib/pacman/sync

# 2. Install the new package
pacman -S <pkg>

# 3. Verify that all dependencies are satisfied
pacman -Qi <pkg>

# 4. Perform a full upgrade to catch any hidden conflicts
pacman -Syu

Need More Context?

If you have specific packages listed in IgnorePkg or are using a non‑standard pacman version, let me know so I can tailor the advice further.