.. _contrib:

Contrib Commands
################

Contrib is an sh sub-module that provides friendly wrappers to useful commands.
Typically, the commands being wrapped are unintuitive, and the contrib version
makes them intuitive.

.. note::

    Contrib commands should be considered generally unstable. They will grow and change as the community figures out the
    best interface for them.

Commands
========

Sudo
----

Allows you to enter your password from the terminal at runtime, or as a string
in your script.

.. py:function:: sudo(password=None, *args, **kwargs)

    Call sudo with ``password``, if specified, else ask the executing user for a
    password at runtime via :func:`getpass.getpass`.

.. seealso:: :ref:`contrib_sudo`

.. _contrib_git:

Git
---

Many git commands use a pager for output, which can cause an unexpected behavior
when run through sh.  To account for this, the contrib version sets
``_tty_out=False`` for all git commands.

.. py:function:: git(*args, **kwargs)

    Call git with STDOUT connected to a pipe, instead of a TTY.

.. code-block:: python

    from sh.contrib import git
    repo_log = git.log()

.. seealso:: :ref:`faq_tty_out` and :ref:`faq_color_output`

.. _contrib_ssh:

SSH
---

.. versionadded:: 1.13.0

SSH password-based logins :ref:`can be a pain <tutorial2>`. This contrib command performs all of the ugly setup and
provides a clean interface to using SSH.

.. py:function:: ssh(interact=None, password=None, prompt_match=None, login_success=None, *args, **kwargs)

    :param interact: A callback to handle SSH session interaction *after* login is successful. Required.
    :param password: A password string or a function that returns a password string. Optional. If not provided, :func:`getpass.getpass` is used.
    :param prompt_match: The string to match in order to determine when to provide SSH with the password. Or a function
            that matches on the output. Optional.
    :param login_success: A function to determine if SSH login is successful. Optional.

The ``interact`` parameter takes a callback with a signature that is slightly different to the function callbacks for
:ref:`redirection <red_func>`:

.. py:function:: fn(content, stdin_queue)
    
    :param content: An instance of an ephemeral :ref:`SessionContent <session_content>` class whose job is to hold the
            characters that the SSH session has written to STDOUT.
    :param stdin_queue: A :class:`queue.Queue` object to communicate with STDIN programmatically.

``password`` can be simply a string that will be used to type the password. If it's not provided, it will be read from STDIN
at runtime via :func:`getpass.getpass`. It can also be a callable that returns the password string.

``prompt_match`` is a string to match before the contrib command will provide the SSH process with the password. It is
optional, and if left unspecified, will default to "password: ". It can also be a callable that is called on a
:ref:`SessionContent <session_content>` instance and returns ``True`` or ``False`` for a match.

``login_success`` is a function that takes a :ref:`SessionContent <session_content>` object and returns a boolean for
whether or not a successful login occurred. It is optional, and if unspecified, simply evaluates to ``True``, meaning
any password submission results in a successful login (obviously not always correct). It is recommended that you specify
this.

.. _session_content:

.. py:class:: SessionContent()

    This class contains a record lines and characters written to the SSH processes's STDOUT. It should be all you need
    from the callbacks to determine how to interact with the SSH process.

.. py:attribute:: SessionContent.chars
    
    :type: :class:`collections.deque`
    
    The previous 50,000 characters.

.. py:attribute:: SessionContent.lines
    
    :type: :class:`collections.deque`
    
    The previous 5,000 lines.

.. py:attribute:: SessionContent.line_chars
    
    :type: list

    The characters in the line currently being aggregated.

.. py:attribute:: SessionContent.cur_line
    
    :type: str

    A string of the line currently being aggregated.

.. py:attribute:: SessionContent.last_line
    
    :type: str

    The previous line.

.. py:attribute:: SessionContent.cur_char
    
    :type: str

    The currently written character.


.. _contrib_bash:

Bash
---

Often users may find themselves having to run bash commands directly, whether due
to commands having special characters (e.g. dash, or dot) or other reasons. 
This can lead into recurrently having to bake the ``bash`` command to call it directly. To 
account for this, the contrib version provides a ``bash`` command baked in:

.. py:function:: bash(*args, **kwargs)

    Call bash with the prefix of "bash -c [...]".

.. code-block:: python

    from sh.contrib import bash

    # Calling commands directly
    bash.ls() # equivallent to "bash -c ls"

    # Or adding the full commands
    bash("command-with-dashes args")


Extending
=========

For developers.

To extend contrib, simply decorate a function in sh with the ``@contrib``
decorator, and pass in the name of the command you wish to shadow to the
decorator.  This method must return an instance of :ref:`Command
<command_class>`:

.. code-block:: python

    @contrib("ls")
    def my_ls(original):
        ls = original.bake("-l")
        return ls

Now you can run your custom contrib command from your scripts, and you'll be
using the command returned from your decorated function:


.. code-block:: python

    from sh.contrib import ls

    # executing: ls -l
    print(ls("/"))

For even more flexibility, you can design your contrib command to rewrite its
options based on *executed* arguments.  For example, say you only wish to set a
command's argument if another argument is set.  You can accomplish it like this:

.. code-block:: python

    @contrib("ls")
    def my_ls(original):
        def process(args, kwargs):
            if "-a" in args:
                args.append("-L")
            return args, kwargs

        ls = original.bake("-l")
        return ls, process

Returning a process function along with the command will tell sh to use that
function to preprocess the arguments at execution time using the
:ref:`_arg_preprocess <preprocess>` special kwarg.
