7994fd1d54
git-subtree-dir: third_party/nix
git-subtree-mainline: cf8cd640c1
git-subtree-split: be66c7a6b24e3c3c6157fd37b86c7203d14acf10
86 lines
3.1 KiB
XML
86 lines
3.1 KiB
XML
<chapter xmlns="http://docbook.org/ns/docbook"
|
||
xmlns:xlink="http://www.w3.org/1999/xlink"
|
||
xmlns:xi="http://www.w3.org/2001/XInclude"
|
||
version="5.0"
|
||
xml:id='sec-garbage-collection'>
|
||
|
||
<title>Garbage Collection</title>
|
||
|
||
<para><command>nix-env</command> operations such as upgrades
|
||
(<option>-u</option>) and uninstall (<option>-e</option>) never
|
||
actually delete packages from the system. All they do (as shown
|
||
above) is to create a new user environment that no longer contains
|
||
symlinks to the “deleted” packages.</para>
|
||
|
||
<para>Of course, since disk space is not infinite, unused packages
|
||
should be removed at some point. You can do this by running the Nix
|
||
garbage collector. It will remove from the Nix store any package
|
||
not used (directly or indirectly) by any generation of any
|
||
profile.</para>
|
||
|
||
<para>Note however that as long as old generations reference a
|
||
package, it will not be deleted. After all, we wouldn’t be able to
|
||
do a rollback otherwise. So in order for garbage collection to be
|
||
effective, you should also delete (some) old generations. Of course,
|
||
this should only be done if you are certain that you will not need to
|
||
roll back.</para>
|
||
|
||
<para>To delete all old (non-current) generations of your current
|
||
profile:
|
||
|
||
<screen>
|
||
$ nix-env --delete-generations old</screen>
|
||
|
||
Instead of <literal>old</literal> you can also specify a list of
|
||
generations, e.g.,
|
||
|
||
<screen>
|
||
$ nix-env --delete-generations 10 11 14</screen>
|
||
|
||
To delete all generations older than a specified number of days
|
||
(except the current generation), use the <literal>d</literal>
|
||
suffix. For example,
|
||
|
||
<screen>
|
||
$ nix-env --delete-generations 14d</screen>
|
||
|
||
deletes all generations older than two weeks.</para>
|
||
|
||
<para>After removing appropriate old generations you can run the
|
||
garbage collector as follows:
|
||
|
||
<screen>
|
||
$ nix-store --gc</screen>
|
||
|
||
The behaviour of the gargage collector is affected by the
|
||
<literal>keep-derivations</literal> (default: true) and <literal>keep-outputs</literal>
|
||
(default: false) options in the Nix configuration file. The defaults will ensure
|
||
that all derivations that are build-time dependencies of garbage collector roots
|
||
will be kept and that all output paths that are runtime dependencies
|
||
will be kept as well. All other derivations or paths will be collected.
|
||
(This is usually what you want, but while you are developing
|
||
it may make sense to keep outputs to ensure that rebuild times are quick.)
|
||
|
||
If you are feeling uncertain, you can also first view what files would
|
||
be deleted:
|
||
|
||
<screen>
|
||
$ nix-store --gc --print-dead</screen>
|
||
|
||
Likewise, the option <option>--print-live</option> will show the paths
|
||
that <emphasis>won’t</emphasis> be deleted.</para>
|
||
|
||
<para>There is also a convenient little utility
|
||
<command>nix-collect-garbage</command>, which when invoked with the
|
||
<option>-d</option> (<option>--delete-old</option>) switch deletes all
|
||
old generations of all profiles in
|
||
<filename>/nix/var/nix/profiles</filename>. So
|
||
|
||
<screen>
|
||
$ nix-collect-garbage -d</screen>
|
||
|
||
is a quick and easy way to clean up your system.</para>
|
||
|
||
<xi:include href="garbage-collector-roots.xml" />
|
||
|
||
</chapter>
|