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+---
+layout: default
+title: Portage cheat sheet
+date: 2026-06-08 23:08 +0200
+tags: Gentoo Portage
+---
+
+h3. Disallow installation of new slot (@NS@) version on update.
+
+*Problem:* there is a package that comes with separate slot for every version.
+Notable example is _sys-kernel/gentoo-sources_. Each @@world@ update attempt
+tries to install new package slot. If kernel is not to be updated, not only
+additional files will take space unnecessarily, but if @emerge --depclean@ is
+run afterwards, the current kernel sources are selected for removal (!).
+
+*Solution:* mask all package slots
+
+{% highlight file caption=/etc/portage/package.mask/kernel %}
+sys-kernel/gentoo-sources
+{% endhighlight %}
+
+then unmask the only slot that is to be kept installed:
+
+{% highlight file caption=/etc/portage/package.unmask %}
+sys-kernel/gentoo-sources:6.6.142
+{% endhighlight %}
+
+*Notes:*
+* masking by version @>@ installed version will not work, as @emerge@ may
+pick for installation any unmasked slot below installed version,
+* masking both @>@ and @<@ installed version is somewhat redundant,
+* @emerge@ does not recognize @!@ atom operator.