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.

                                                                                      nix3-log(1)