# Specific config details

## Custom Prompts

Changed in version 5.0.

From IPython 5, prompts are produced as a list of Pygments tokens, which are tuples of (token_type, text). You can customise prompts by writing a method which generates a list of tokens.

There are four kinds of prompt:

- The in prompt is shown before the first line of input (default like `In [1]:`).
- The continuation prompt is shown before further lines of input (default like `...:`).
- The rewrite prompt is shown to highlight how special syntax has been interpreted (default like `----->`).
- The out prompt is shown before the result from evaluating the input (default like `Out[1]:`).

Custom prompts are supplied together as a class. If you want to customise only some of the prompts, inherit from `IPython.terminal.prompts.Prompts`, which defines the defaults. The required interface is like this:

class `MyPrompts`(shell)

  Prompt style definition. shell is a reference to the `TerminalInteractiveShell` instance.

  `in_prompt_tokens`(cli=None)
  `continuation_prompt_tokens`(self, cli=None, width=None)
  `rewrite_prompt_tokens`()
  `out_prompt_tokens`()

    Return the respective prompts as lists of `(token_type, text)` tuples.

    For continuation prompts, width is an integer representing the width of the prompt area in terminal columns.

    cli, where used, is the prompt_toolkit `CommandLineInterface` instance. This is mainly for compatibility with the API prompt_toolkit expects.

Here is an example Prompt class that will show the current working directory in the input prompt:

    from IPython.terminal.prompts import Prompts, Token
    import os

    class MyPrompt(Prompts):
         def in_prompt_tokens(self, cli=None):
             return [(Token, os.getcwd()),
                     (Token.Prompt, ' >>>')]

To set the new prompt, assign it to the `prompts` attribute of the IPython shell:

    In [2]: ip = get_ipython()
       ...: ip.prompts = MyPrompt(ip)

    /home/bob >>> # it works

See `IPython/example/utils/cwd_prompt.py` for an example of how to write an extensions to customise prompts.

Inside IPython or in a startup script, you can use a custom prompts class by setting `get_ipython().prompts` to an instance of the class. In configuration, `TerminalInteractiveShell.prompts_class` may be set to either the class object, or a string of its full importable name.

To include invisible terminal control sequences in a prompt, use `Token.ZeroWidthEscape` as the token type. Tokens with this type are ignored when calculating the width.

Colours in the prompt are determined by the token types and the highlighting style; see below for more details. The tokens used in the default prompts are `Prompt`, `PromptNum`, `OutPrompt` and `OutPromptNum`.

## Terminal Colors

Changed in version 5.0.

There are two main configuration options controlling colours.

`InteractiveShell.colors` sets the colour of tracebacks and object info (the output from e.g. `zip?`). It may also affect other things if the option below is set to `'legacy'`. It has four case-insensitive values: `'nocolor', 'neutral', 'linux', 'lightbg'`. The default is neutral, which should be legible on either dark or light terminal backgrounds. linux is optimised for dark backgrounds and lightbg for light ones.

`TerminalInteractiveShell.highlighting_style` determines prompt colours and syntax highlighting. It takes the name (as a string) or class (as a subclass of `pygments.style.Style`) of a Pygments style, or the special value `'legacy'` to pick a style in accordance with `InteractiveShell.colors`.

You can see the Pygments styles available on your system by running:

    import pygments
    list(pygments.styles.get_all_styles())

Additionally, `TerminalInteractiveShell.highlighting_style_overrides` can override specific styles in the highlighting. It should be a dictionary mapping Pygments token types to strings defining the style. See Pygments’ documentation for the language used to define styles.

### Colors in the pager

On some systems, the default pager has problems with ANSI colour codes. To configure your default pager to allow these:

1. Set the environment PAGER variable to `less`.
2. Set the environment LESS variable to `-r` (plus any other options you always want to pass to less by default). This tells less to properly interpret control sequences, which is how color information is given to your terminal.

## Editor configuration

IPython can integrate with text editors in a number of different ways:

- Editors (such as (X)Emacs, vim and TextMate) can send code to IPython for execution.
- IPython’s `%edit` magic command can open an editor of choice to edit a code block.

The %edit command (and its alias %ed) will invoke the editor set in your environment as `EDITOR`. If this variable is not set, it will default to vi under Linux/Unix and to notepad under Windows. You may want to set this variable properly and to a lightweight editor which doesn’t take too long to start (that is, something other than a new instance of Emacs). This way you can edit multi-line code quickly and with the power of a real editor right inside IPython.

You can also control the editor by setting `TerminalInteractiveShell.editor` in `ipython_config.py`.

### Vim

Paul Ivanov’s vim-ipython provides powerful IPython integration for vim.

### (X)Emacs

If you are a dedicated Emacs user, and want to use Emacs when IPython’s `%edit` magic command is called you should set up the Emacs server so that new requests are handled by the original process. This means that almost no time is spent in handling the request (assuming an Emacs process is already running). For this to work, you need to set your EDITOR environment variable to ‘emacsclient’. The code below, supplied by Francois Pinard, can then be used in your `.emacs` file to enable the server:

    (defvar server-buffer-clients)
    (when (and (fboundp 'server-start) (string-equal (getenv "TERM") 'xterm))
      (server-start)
      (defun fp-kill-server-with-buffer-routine ()
        (and server-buffer-clients (server-done)))
      (add-hook 'kill-buffer-hook 'fp-kill-server-with-buffer-routine))

Thanks to the work of Alexander Schmolck and Prabhu Ramachandran, currently (X)Emacs and IPython get along very well in other ways.

With (X)EMacs >= 24, You can enable IPython in python-mode with:

    (require 'python)
    (setq python-shell-interpreter "ipython")

## Keyboard Shortcuts

Changed in version 5.0.

You can customise keyboard shortcuts for terminal IPython. Put code like this in a startup file:

    from IPython import get_ipython
    from prompt_toolkit.enums import DEFAULT_BUFFER
    from prompt_toolkit.keys import Keys
    from prompt_toolkit.filters import HasFocus, HasSelection, ViInsertMode, EmacsInsertMode

    ip = get_ipython()
    insert_mode = ViInsertMode() | EmacsInsertMode()

    def insert_unexpected(event):
        buf = event.current_buffer
        buf.insert_text('The Spanish Inquisition')

    # Register the shortcut if IPython is using prompt_toolkit
    if getattr(ip, 'pt_cli'):
        registry = ip.pt_cli.application.key_bindings_registry
        registry.add_binding(Keys.ControlN,
                         filter=(HasFocus(DEFAULT_BUFFER)
                                 & ~HasSelection()
                                 & insert_mode))(insert_unexpected)

For more information on filters and what you can do with the `event` object, see the prompt_toolkit docs.