nix3-log(1)

    Warning
    This program is experimental and its interface is subject to change.

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/vaph2hfdmnipqr90v6g5mcdn8h5p5iss-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 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/<store-path-base-name>, where <store-path-base-name> is the store path base name of 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 from the store object metadata.

Options

  Common evaluation options

•   --arg name expr

    Pass the value expr as the argument name to Nix functions.

•   --arg-from-file name path

    Pass the contents of file path as the argument name to Nix functions.

•   --arg-from-stdin name

    Pass the contents of stdin as the argument name to Nix functions.

•   --argstr name string

    Pass the string string as the argument name to Nix functions.

•   --debugger

    Start an interactive environment if evaluation fails.

•   --eval-store store-url

    The URL of the Nix store to use for evaluation, i.e. to store derivations (.drv files) and inputs referenced by them.

•   --impure

    Allow access to mutable paths and repositories.

•   --include / -I path

    Add path to search path entries used to resolve lookup paths

    This option may be given multiple times.

    Paths added through -I take precedence over the nix-path configuration setting and the NIX_PATH environment variable.

•   --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.

        DEPRECATED

        Use --no-use-registries instead.

•   --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.

•   --output-lock-file flake-lock-path

    Write the given lock file instead of flake.lock within the top-level flake.

•   --override-input input-path flake-url

    Override a specific flake input (e.g. dwarffs/nixpkgs). The input path must not be empty. This implies --no-write-lock-file.

•   --recreate-lock-file

    Recreate the flake’s lock file from scratch.

        DEPRECATED

        Use nix flake update instead.

•   --reference-lock-file flake-lock-path

    Read the given lock file instead of flake.lock within the top-level flake.

•   --update-input input-path

    Update a specific flake input (ignoring its previous entry in the lock file).

        DEPRECATED

        Use nix flake update instead.

  Logging-related options

•   --debug

    Set the logging verbosity level to ‘debug’.

•   --log-format format

    Set the format of log output; one of raw, internal-json, bar or bar-with-logs.

•   --print-build-logs / -L

    Print full build logs on standard error.

•   --quiet

    Decrease the logging verbosity level.

•   --verbose / -v

    Increase the logging verbosity level.

  Miscellaneous global options

•   --help

    Show usage information.

•   --offline

    Disable substituters and consider all previously downloaded files up-to-date.

•   --option name value

    Set the Nix configuration setting name to value (overriding nix.conf).

•   --refresh

    Consider all previously downloaded files out-of-date.

•   --repair

    During evaluation, rewrite missing or corrupted files in the Nix store. During building, rebuild missing or corrupted store paths.

•   --version

    Show version information.

  Options that change the interpretation of installables

•   --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 is read from standard input. Implies --impure.

    Note

    See man nix.conf for overriding configuration settings with command line flags.