docs-archive/1.10.13/_sources/howto/operator/bash.rst.txt

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.. _howto/operator:BashOperator:

BashOperator
============

Use the :class:`~airflow.operators.bash_operator.BashOperator` to execute
commands in a `Bash <https://www.gnu.org/software/bash/>`__ shell.

.. exampleinclude:: ../../../airflow/example_dags/example_bash_operator.py
    :language: python
    :start-after: [START howto_operator_bash]
    :end-before: [END howto_operator_bash]

Templating
----------

You can use :ref:`Jinja templates <jinja-templating>` to parameterize the
``bash_command`` argument.

.. exampleinclude:: ../../../airflow/example_dags/example_bash_operator.py
    :language: python
    :start-after: [START howto_operator_bash_template]
    :end-before: [END howto_operator_bash_template]


.. warning::

    Care should be taken with "user" input or when using Jinja templates in the
    ``bash_command``, as this bash operator does not perform any escaping or
    sanitization of the command.

    This applies mostly to using "dag_run" conf, as that can be submitted via
    users in the Web UI. Most of the default template variables are not at
    risk.

For example, do **not** do this:

.. code-block:: python

    bash_task = BashOperator(
        task_id="bash_task",
        bash_command='echo "Here is the message: \'{{ dag_run.conf["message"] if dag_run else "" }}\'"',
    )

Instead, you should pass this via the ``env`` kwarg and use double-quotes
inside the bash_command, as below:

.. code-block:: python

    bash_task = BashOperator(
        task_id="bash_task",
        bash_command='echo "here is the message: \'$message\'"',
        env={'message': '{{ dag_run.conf["message"] if dag_run else "" }}'},
    )

Troubleshooting
---------------

Jinja template not found
""""""""""""""""""""""""

Add a space after the script name when directly calling a Bash script with
the ``bash_command`` argument. This is because Airflow tries to apply a Jinja
template to it, which will fail.

.. code-block:: python

    t2 = BashOperator(
        task_id='bash_example',

        # This fails with 'Jinja template not found' error
        # bash_command="/home/batcher/test.sh",

        # This works (has a space after)
        bash_command="/home/batcher/test.sh ",
        dag=dag)