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nix/doc/manual/source/command-ref/nix-store/gc.md
Adam Dinwoodie 972915cabd docs: remove incorrect claim re gc --print-dead 
Per #7591, the `nix-store --gc --print-dead` command does not provide
any feedback about the amount of disk space that is used by dead store
paths.  It looks like this has been the case since 7ab68961e (* Garbage
collector: added an option `--use-atime' to delete paths in...,
2008-09-17).

Update the nix-store documentation to remove the claim that this is
function that `nix-store --gc --print-dead` performs.
2025-10-28 09:47:25 +00:00

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Name

nix-store --gc - run garbage collection

Synopsis

nix-store --gc [--print-roots | --print-live | --print-dead] [--max-freed bytes]

Description

Without additional flags, the operation --gc performs a garbage collection on the Nix store. That is, all paths in the Nix store not reachable via file system references from a set of “roots”, are deleted.

The following suboperations may be specified:

  • --print-roots

    This operation prints on standard output the set of roots used by the garbage collector.

  • --print-live

    This operation prints on standard output the set of “live” store paths, which are all the store paths reachable from the roots. Live paths should never be deleted, since that would break consistency — it would become possible that applications are installed that reference things that are no longer present in the store.

  • --print-dead

    This operation prints out on standard output the set of “dead” store paths, which is just the opposite of the set of live paths: any path in the store that is not live (with respect to the roots) is dead.

By default, all unreachable paths are deleted. The following options control what gets deleted and in what order:

  • --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.

The behaviour of the collector is also influenced by the keep-outputs and keep-derivations settings in the Nix configuration file.

By default, the collector prints the total number of freed bytes when it finishes (or when it is interrupted).

{{#include ./opt-common.md}}

{{#include ../opt-common.md}}

{{#include ../env-common.md}}

Examples

To delete all unreachable paths, just do:

$ nix-store --gc
deleting `/nix/store/kq82idx6g0nyzsp2s14gfsc38npai7lf-cairo-1.0.4.tar.gz.drv'
...
8825586 bytes freed (8.42 MiB)

To delete at least 100 MiBs of unreachable paths:

$ nix-store --gc --max-freed $((100 * 1024 * 1024))