This program is experimental and its interface is subject to change.
nix why-depends - show why a package has another package in its closure
nix why-depends [option...] package dependency
Show one path through the dependency graph leading from Hello to Glibc:
# nix why-depends nixpkgs#hello nixpkgs#glibc /nix/store/v5sv61sszx301i0x6xysaqzla09nksnd-hello-2.10 └───bin/hello: …...................../nix/store/9l06v7fc38c1x3r2iydl15ksgz0ysb82-glibc-2.32/lib/ld-linux-x86-64.… → /nix/store/9l06v7fc38c1x3r2iydl15ksgz0ysb82-glibc-2.32
Show all files and paths in the dependency graph leading from Thunderbird to libX11:
# nix why-depends --all nixpkgs#thunderbird nixpkgs#xorg.libX11 /nix/store/qfc8729nzpdln1h0hvi1ziclsl3m84sr-thunderbird-78.5.1 ├───lib/thunderbird/libxul.so: …6wrw-libxcb-1.14/lib:/nix/store/adzfjjh8w25vdr0xdx9x16ah4f5rqrw5-libX11-1.7.0/lib:/nix/store/ssf… │ → /nix/store/adzfjjh8w25vdr0xdx9x16ah4f5rqrw5-libX11-1.7.0 ├───lib/thunderbird/libxul.so: …pxyc-libXt-1.2.0/lib:/nix/store/1qj29ipxl2fyi2b13l39hdircq17gnk0-libXdamage-1.1.5/lib:/nix/store… │ → /nix/store/1qj29ipxl2fyi2b13l39hdircq17gnk0-libXdamage-1.1.5 │ ├───lib/libXdamage.so.1.1.0: …-libXfixes-5.0.3/lib:/nix/store/adzfjjh8w25vdr0xdx9x16ah4f5rqrw5-libX11-1.7.0/lib:/nix/store/9l0… │ │ → /nix/store/adzfjjh8w25vdr0xdx9x16ah4f5rqrw5-libX11-1.7.0 …
Show why Glibc depends on itself:
# nix why-depends nixpkgs#glibc nixpkgs#glibc /nix/store/9df65igwjmf2wbw0gbrrgair6piqjgmi-glibc-2.31 └───lib/ld-2.31.so: …che Do not use /nix/store/9df65igwjmf2wbw0gbrrgair6piqjgmi-glibc-2.31/etc/ld.so.cache. --… → /nix/store/9df65igwjmf2wbw0gbrrgair6piqjgmi-glibc-2.31
Show why Geeqie has a build-time dependency on
# nix why-depends --derivation nixpkgs#geeqie nixpkgs#systemd /nix/store/drrpq2fqlrbj98bmazrnww7hm1in3wgj-geeqie-1.4.drv └───/: …atch.drv",["out"]),("/nix/store/qzh8dyq3lfbk3i1acbp7x9wh3il2imiv-gtk+3-3.24.21.drv",["dev"]),("/… → /nix/store/qzh8dyq3lfbk3i1acbp7x9wh3il2imiv-gtk+3-3.24.21.drv └───/: …16.0.drv",["dev"]),("/nix/store/8kp79fyslf3z4m3dpvlh6w46iaadz5c2-cups-2.3.3.drv",["dev"]),("/nix… → /nix/store/8kp79fyslf3z4m3dpvlh6w46iaadz5c2-cups-2.3.3.drv └───/: ….3.1.drv",["out"]),("/nix/store/yd3ihapyi5wbz1kjacq9dbkaq5v5hqjg-systemd-246.4.drv",["dev"]),("/… → /nix/store/yd3ihapyi5wbz1kjacq9dbkaq5v5hqjg-systemd-246.4.drv
Nix automatically determines potential runtime dependencies between
store paths by scanning for the hash parts of store paths. For
instance, if there exists a store path
/nix/store/9df65igwjmf2wbw0gbrrgair6piqjgmi-glibc-2.31, and a file
inside another store path contains the string
9df65igw…, then the
latter store path refers to the former, and thus might need it at
runtime. Nix always maintains the existence of the transitive closure
of a store path under the references relationship; it is therefore not
possible to install a store path without having all of its references
Sometimes Nix packages end up with unexpected runtime dependencies; for instance, a reference to a compiler might accidentally end up in a binary, causing the former to be in the latter's closure. This kind of closure size bloat is undesirable.
nix why-depends allows you to diagnose the cause of such issues. It
shows why the store path package depends on the store path
dependency, by showing a shortest sequence in the references graph
from the former to the latter. Also, for each node along this path, it
shows a file fragment containing a reference to the next store path in
To show why derivation package has a build-time rather than runtime
dependency on derivation dependency, use
Show all edges in the dependency graph leading from package to dependency, rather than just a shortest path.
For each edge in the dependency graph, show the files in the parent that cause the dependency.
Pass the value expr as the argument name to Nix functions.
Pass the string string as the argument name to Nix functions.
Start an interactive environment if evaluation fails.
The URL of the Nix store to use for evaluation, i.e. to store derivations (
.drvfiles) and inputs referenced by them.
Allow access to mutable paths and repositories.
Add path to the Nix search path. The Nix search path is initialized from the colon-separated
NIX_PATHenvironment variable, and is used to look up the location of Nix expressions using paths enclosed in angle brackets (i.e.,
For instance, passing
-I /home/eelco/Dev -I /etc/nixos
will cause Nix to look for paths relative to
/etc/nixos, in that order. This is equivalent to setting the
NIX_PATHenvironment variable to
It is also possible to match paths against a prefix. For example, passing
-I nixpkgs=/home/eelco/Dev/nixpkgs-branch -I /etc/nixos
will cause Nix to search for
If a path in the Nix search path starts with
https://, it is interpreted as the URL of a tarball that will be downloaded and unpacked to a temporary location. The tarball must consist of a single top-level directory. For example, passing
tells Nix to download and use the current contents of the
masterbranch in the
The URLs of the tarballs from the official
nixos.orgchannels (see the manual page for
nix-channel) can be abbreviated as
channel:<channel-name>. For instance, the following two flags are equivalent:
-I nixpkgs=channel:nixos-21.05 -I nixpkgs=https://nixos.org/channels/nixos-21.05/nixexprs.tar.xz
You can also fetch source trees using flake URLs and add them to the search path. For instance,
specifies that the prefix
nixpkgsshall refer to the source tree downloaded from the
nixpkgsentry in the flake registry. Similarly,
<nixpkgs>refer to a particular branch of the
NixOS/nixpkgsrepository on GitHub.
Override the flake registries, redirecting original-ref to resolved-ref.
Commit changes to the flake's lock file.
Use the inputs of the specified flake as registry entries.
Don't allow lookups in the flake registries.
Do not allow any updates to the flake's lock file.
Do not write the flake's newly generated lock file.
Write the given lock file instead of
flake.lockwithin the top-level flake.
Override a specific flake input (e.g.
dwarffs/nixpkgs). This implies
Recreate the flake's lock file from scratch.
nix flake updateinstead.
Read the given lock file instead of
flake.lockwithin the top-level flake.
Update a specific flake input (ignoring its previous entry in the lock file).
nix flake updateinstead.
Set the logging verbosity level to 'debug'.
Set the format of log output; one of
Print full build logs on standard error.
Decrease the logging verbosity level.
Increase the logging verbosity level.
Show usage information.
Disable substituters and consider all previously downloaded files up-to-date.
Set the Nix configuration setting name to value (overriding
Consider all previously downloaded files out-of-date.
During evaluation, rewrite missing or corrupted files in the Nix store. During building, rebuild missing or corrupted store paths.
Show version information.
Operate on the store derivation rather than its outputs.
Interpret installables as attribute paths relative to the Nix expression expr.
Interpret installables as attribute paths relative to the Nix expression stored in file. If file is the character -, then a Nix expression will be read from standard input. Implies
man nix.conffor overriding configuration settings with command line flags.