Name

nix-collect-garbage - delete unreachable store objects

Synopsis

nix-collect-garbage [--delete-old] [-d] [--delete-older-than period] [--keep-min generations] [--keep-max generations] [--max-freed bytes] [--dry-run]

Description

The command nix-collect-garbage is mostly an alias of nix-store --gc. That is, it deletes all unreachable store objects in the Nix store to clean up your system.

However, it provides more additional options, --delete-old, --delete-older-than, --keep-min, and --keep-max, which also delete old profiles, allowing potentially more store objects to be deleted because profiles are also garbage collection roots. These options are the equivalent of running nix-env --delete-generations with various augments on multiple profiles, prior to running nix-collect-garbage (or just nix-store --gc) without any flags.

Note

Deleting previous configurations makes rollbacks to them impossible.

These flags should be used with care, because they potentially delete generations of profiles used by other users on the system.

Locations searched for profiles

nix-collect-garbage cannot know about all profiles; that information doesn't exist. Instead, it looks in a few locations, and acts on all profiles it finds there:

The default profile locations as specified in the profiles section of the manual.
NOTE

Not stable; subject to change

Do not rely on this functionality; it just exists for migration purposes and may change in the future. These deprecated paths remain a private implementation detail of Nix.

$NIX_STATE_DIR/profiles and $NIX_STATE_DIR/profiles/per-user.

With the exception of $NIX_STATE_DIR/profiles/per-user/root and $NIX_STATE_DIR/profiles/default, these directories are no longer used by other commands. nix-collect-garbage looks there anyways in order to clean up profiles from older versions of Nix.

Options

These options are for deleting old profiles prior to deleting unreachable store objects.

--delete-old / -d

Delete all old generations of profiles.

This is the equivalent of invoking nix-env --delete-generations old on each found profile.
--delete-older-than period

Delete all generations of profiles older than the specified amount (except for the generations that were active at that point in time). period is a value such as 30d, which would mean 30 days.

This is the equivalent of invoking nix-env --delete-generations <period> on each found profile. See the documentation of that command for additional information about the period argument.
--keep-min generations

Minimum amount of generations to keep after deletion.
--keep-max generations

Maximum amount of generations to keep after deletion.
--max-freed bytes

Keep deleting paths until at least bytes bytes have been deleted, then stop. The argument bytes can be followed by the multiplicative suffix K, M, G or T, denoting KiB, MiB, GiB or TiB units.

Examples

Delete all older

To delete from the Nix store everything that is not used by the current generations of each profile, do

$ nix-collect-garbage -d

Keep most-recent by time (number fo days) and trim by amount

This command will delete generations older than a week if possible, while keeping an amount of generations between 10 and 20.

$ nix-collect-garbage --delete-older-than 7d --keep-min 10 --keep-max 20

If there were more than 20 generations built in the past week, it will only keep 20 most recent ones. If there were less than 10 generations built in the past week, it will keep even older generations, until there is 10.

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