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# Shell Tasks
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 ## ShellTask
 <div class='class-sig' id='prefect-tasks-shell-shelltask'><p class="prefect-sig">class </p><p class="prefect-class">prefect.tasks.shell.ShellTask</p>(command=None, env=None, helper_script=None, shell="bash", return_all=False, **kwargs)<span class="source"><a href="https://github.com/PrefectHQ/prefect/blob/master/src/prefect/tasks/shell.py#L10">[source]</a></span></div>

Task for running arbitrary shell commands.

**Args**:     <ul class="args"><li class="args">`command (string, optional)`: shell command to be executed; can also be         provided post-initialization by calling this task instance     </li><li class="args">`env (dict, optional)`: dictionary of environment variables to use for         the subprocess; can also be provided at runtime     </li><li class="args">`helper_script (str, optional)`: a string representing a shell script, which         will be executed prior to the `command` in the same process. Can be used to         change directories, define helper functions, etc. when re-using this Task         for different commands in a Flow     </li><li class="args">`shell (string, optional)`: shell to run the command with; defaults to "bash"     </li><li class="args">`return_all (bool, optional)`: boolean specifying whether this task should return all lines of stdout         as a list, or just the last line as a string; defaults to `False`     </li><li class="args">`**kwargs`: additional keyword arguments to pass to the Task constructor</li></ul>**Example**:     
```python
    from prefect import Flow
    from prefect.tasks.shell import ShellTask

    task = ShellTask(helper_script="cd ~")
    with Flow("My Flow") as f:
        # both tasks will be executed in home directory
        contents = task(command='ls')
        mv_file = task(command='mv .vimrc /.vimrc')

    out = f.run()

```

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 | <div class='method-sig' id='prefect-tasks-shell-shelltask-run'><p class="prefect-class">prefect.tasks.shell.ShellTask.run</p>(command=None, env=None)<span class="source"><a href="https://github.com/PrefectHQ/prefect/blob/master/src/prefect/tasks/shell.py#L59">[source]</a></span></div>
<p class="methods">Run the shell command.<br><br>**Args**:     <ul class="args"><li class="args">`command (string)`: shell command to be executed; can also be         provided at task initialization. Any variables / functions defined in         `self.helper_script` will be available in the same process this command         runs in     </li><li class="args">`env (dict, optional)`: dictionary of environment variables to use for         the subprocess</li></ul>**Returns**:     <ul class="args"><li class="args">`stdout (string)`: if `return_all` is `False` (the default), only the last line of stdout         is returned, otherwise all lines are returned, which is useful for passing         result of shell command to other downstream tasks. If there is no output, `None` is returned.</li></ul>**Raises**:     <ul class="args"><li class="args">`prefect.engine.signals.FAIL`: if command has an exit code other         than 0</li></ul></p>|

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<p class="auto-gen">This documentation was auto-generated from commit <a href='https://github.com/PrefectHQ/prefect/commit/n/a'>n/a</a> </br>on December 17, 2019 at 21:20 UTC</p>