Name¶

nix log - show the build log of the specified packages or paths, if available

Synopsis¶

nix log [option…] installable

Examples¶

•

Get the build log of GNU Hello:

# nix log nixpkgs#hello

•

Get the build log of a specific store path:

# nix log /nix/store/lmngj4wcm9rkv3w4dfhzhcyij3195hiq-thunderbird-52.2.1

•

Get a build log from a specific binary cache:

# nix log --store https://cache.nixos.org nixpkgs#hello

Description¶

This command prints the log of a previous build of the derivation installable on standard output.

Nix looks for build logs in two places:

• In the directory /nix/var/log/nix/drvs, which contains logs for locally built derivations.
• In the binary caches listed in the substituters setting. Logs should be named <cache>/log/<base-name-of-store-path>, where store-path is a derivation, e.g. https://cache.nixos.org/log/dvmig8jgrdapvbyxb1rprckdmdqx08kv-hello-2.10.drv. For non-derivation store paths, Nix will first try to determine the deriver by fetching the .narinfo file for this store path.

Options¶

Common evaluation options:

• --arg name expr
  Pass the value expr as the argument name to Nix functions.
• --argstr name string
  Pass the string string as the argument name to Nix functions.
• --eval-store store-url
  The Nix store to use for evaluations.
• --impure
  Allow access to mutable paths and repositories.
• --include / -I path
  Add path to the list of locations used to look up <...> file names.
• --override-flake original-ref resolved-ref
  Override the flake registries, redirecting original-ref to resolved-ref.

Common flake-related options:

• --commit-lock-file
  Commit changes to the flake’s lock file.
• --inputs-from flake-url
  Use the inputs of the specified flake as registry entries.
• --no-registries
  Don’t allow lookups in the flake registries. This option is deprecated; use --no-use-registries.
• --no-update-lock-file
  Do not allow any updates to the flake’s lock file.
• --no-write-lock-file
  Do not write the flake’s newly generated lock file.
• --override-input input-path flake-url
  Override a specific flake input (e.g. dwarffs/nixpkgs). This implies --no-write-lock-file.
• --recreate-lock-file
  Recreate the flake’s lock file from scratch.
• --update-input input-path
  Update a specific flake input (ignoring its previous entry in the lock file).

Options that change the interpretation of installables:

• --derivation
  Operate on the store derivation rather than its outputs.
• --expr expr
  Interpret installables as attribute paths relative to the Nix expression expr.
• --file / -f file
  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.