81 lines
3.7 KiB
Markdown
81 lines
3.7 KiB
Markdown
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R""(
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# Examples
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* Show one path through the dependency graph leading from Hello to
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Glibc:
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```console
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# nix why-depends nixpkgs#hello nixpkgs#glibc
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/nix/store/v5sv61sszx301i0x6xysaqzla09nksnd-hello-2.10
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└───bin/hello: …...................../nix/store/9l06v7fc38c1x3r2iydl15ksgz0ysb82-glibc-2.32/lib/ld-linux-x86-64.…
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→ /nix/store/9l06v7fc38c1x3r2iydl15ksgz0ysb82-glibc-2.32
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```
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* Show all files and paths in the dependency graph leading from
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Thunderbird to libX11:
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```console
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# nix why-depends --all nixpkgs#thunderbird nixpkgs#xorg.libX11
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/nix/store/qfc8729nzpdln1h0hvi1ziclsl3m84sr-thunderbird-78.5.1
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├───lib/thunderbird/libxul.so: …6wrw-libxcb-1.14/lib:/nix/store/adzfjjh8w25vdr0xdx9x16ah4f5rqrw5-libX11-1.7.0/lib:/nix/store/ssf…
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│ → /nix/store/adzfjjh8w25vdr0xdx9x16ah4f5rqrw5-libX11-1.7.0
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├───lib/thunderbird/libxul.so: …pxyc-libXt-1.2.0/lib:/nix/store/1qj29ipxl2fyi2b13l39hdircq17gnk0-libXdamage-1.1.5/lib:/nix/store…
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│ → /nix/store/1qj29ipxl2fyi2b13l39hdircq17gnk0-libXdamage-1.1.5
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│ ├───lib/libXdamage.so.1.1.0: …-libXfixes-5.0.3/lib:/nix/store/adzfjjh8w25vdr0xdx9x16ah4f5rqrw5-libX11-1.7.0/lib:/nix/store/9l0…
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│ │ → /nix/store/adzfjjh8w25vdr0xdx9x16ah4f5rqrw5-libX11-1.7.0
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…
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```
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* Show why Glibc depends on itself:
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```console
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# nix why-depends nixpkgs#glibc nixpkgs#glibc
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/nix/store/9df65igwjmf2wbw0gbrrgair6piqjgmi-glibc-2.31
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└───lib/ld-2.31.so: …che Do not use /nix/store/9df65igwjmf2wbw0gbrrgair6piqjgmi-glibc-2.31/etc/ld.so.cache. --…
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→ /nix/store/9df65igwjmf2wbw0gbrrgair6piqjgmi-glibc-2.31
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```
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* Show why Geeqie has a build-time dependency on `systemd`:
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```console
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# nix why-depends --derivation nixpkgs#geeqie nixpkgs#systemd
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/nix/store/drrpq2fqlrbj98bmazrnww7hm1in3wgj-geeqie-1.4.drv
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└───/: …atch.drv",["out"]),("/nix/store/qzh8dyq3lfbk3i1acbp7x9wh3il2imiv-gtk+3-3.24.21.drv",["dev"]),("/…
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→ /nix/store/qzh8dyq3lfbk3i1acbp7x9wh3il2imiv-gtk+3-3.24.21.drv
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└───/: …16.0.drv",["dev"]),("/nix/store/8kp79fyslf3z4m3dpvlh6w46iaadz5c2-cups-2.3.3.drv",["dev"]),("/nix…
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→ /nix/store/8kp79fyslf3z4m3dpvlh6w46iaadz5c2-cups-2.3.3.drv
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└───/: ….3.1.drv",["out"]),("/nix/store/yd3ihapyi5wbz1kjacq9dbkaq5v5hqjg-systemd-246.4.drv",["dev"]),("/…
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→ /nix/store/yd3ihapyi5wbz1kjacq9dbkaq5v5hqjg-systemd-246.4.drv
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```
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# Description
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Nix automatically determines potential runtime dependencies between
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store paths by scanning for the *hash parts* of store paths. For
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instance, if there exists a store path
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`/nix/store/9df65igwjmf2wbw0gbrrgair6piqjgmi-glibc-2.31`, and a file
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inside another store path contains the string `9df65igw…`, then the
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latter store path *refers* to the former, and thus might need it at
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runtime. Nix always maintains the existence of the transitive closure
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of a store path under the references relationship; it is therefore not
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possible to install a store path without having all of its references
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present.
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Sometimes Nix packages end up with unexpected runtime dependencies;
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for instance, a reference to a compiler might accidentally end up in a
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binary, causing the former to be in the latter's closure. This kind of
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*closure size bloat* is undesirable.
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`nix why-depends` allows you to diagnose the cause of such issues. It
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shows why the store path *package* depends on the store path
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*dependency*, by showing a shortest sequence in the references graph
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from the former to the latter. Also, for each node along this path, it
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shows a file fragment containing a reference to the next store path in
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the sequence.
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To show why derivation *package* has a build-time rather than runtime
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dependency on derivation *dependency*, use `--derivation`.
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)""
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