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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, log_stderr=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">`log_stderr (bool, optional)`: boolean specifying whether this task         should log the output from stderr in the case of a non-zero exit code;         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#L65">[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 August 6, 2020 at 13:56 UTC</p>