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Invoking pytask

Invoke pytask from the command line with

$ pytask

Use the following flags to learn more about pytask and its configuration.

$ pytask --version
$ pytask -h | --help

Commands

pytask has multiple commands listed on the main help page.

--8<-- "docs/source/_static/md/help-page.md"

The build command is the default command, meaning the following two calls are identical.

$ pytask
$ pytask build

Display command-specific information by adding the help flag after the command.

$ pytask <command-name> -h/--help

The build command

The build command accepts many options and paths as positional arguments. If no paths are passed via the command line interface, pytask will look for paths in the configuration file. At last, pytask will collect tasks from the current working directory and subsequent folders.

You can also pass any number of paths of directories or modules to the program.

$ pytask path/to/task_module.py path/to/folder

Don't use paths to run task subsets. Use expressions instead. When pytask collects tasks from subpaths of your project, it cannot infer the whole structure of dependencies and products and might run your tasks with missing or outdated dependencies.

Options

Here are a few selected options for the build command.

Showing errors immediately

To show errors immediately when they occur, use

$ pytask --show-errors-immediately

It can be helpful when you have a long-running workflow but want feedback as soon as it is available. See --show-errors-immediately.

Stopping after the first (N) failures

To stop the build of the project after the first n failures, use

$ pytask -x | --stop-after-first-failure  # Stop after the first failure
$ pytask --max-failures 2                 # Stop after the second failure

See -x, --stop-after-first-failure and --max-failures.

Performing a dry-run

Do a dry run with --dry-run to see which tasks will be executed without executing them.

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Explaining why tasks are executed

Use the --explain flag to understand why tasks need to be executed. This shows what changed (source files, dependencies, products, previous tasks) and helps you understand pytask's execution decisions.

--8<-- "docs/source/_static/md/explain.md"

The explanation output respects the --verbose flag:

  • Default verbosity: Shows tasks that would be executed and skipped tasks
  • -v or --verbose 1: Same as default, with summary for persisted and unchanged tasks
  • --verbose 2: Shows detailed information including persisted and unchanged tasks with change reasons

!!! seealso

`pytask` also has a functional interface that is explained in
[this article](../how_to_guides/functional_interface.ipynb).