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https://github.com/szermatt/emacs-bash-completion

Add programmable bash completion to Emacs shell-mode
https://github.com/szermatt/emacs-bash-completion

bash bash-completion emacs emacs-lisp

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Add programmable bash completion to Emacs shell-mode

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# bash-completion for Emacs [![test](https://github.com/szermatt/emacs-bash-completion/workflows/test/badge.svg)](https://github.com/szermatt/emacs-bash-completion/actions) [![melpa](https://melpa.org/packages/bash-completion-badge.svg)](https://melpa.org/#/bash-completion) [![melpa-stable](https://stable.melpa.org/packages/bash-completion-badge.svg)](https://stable.melpa.org/#/bash-completion)



bash-completion.el defines dynamic completion hooks for shell-mode

and shell-command prompts that is based on bash completion.



Bash completion for Emacs:



- is aware of bash builtins, aliases and functions

- does file expansion inside of colon-separated variables

  and after redirections (> or <)

- escapes special characters when expanding file names

- is configurable through programmable bash completion

- works on remote shells, through TRAMP.



However, bash-completion.el only works with bash. If you run

other shells or other interactive programs that support completion,

bash-completion will not be able to help.



A more powerful alternative to bash-completion.el is [MisTTY],

as it works with all shells and most interactive programs that support

completion. On the other hand, MisTTY cannot integrate with Emacs

completion and is not able to provide completion in shell-command

prompts nor in eshell mode.



> [!NOTE]

> While I'm still maintaining bash-completion.el, I've switched

> to [MisTTY] for day-to-day operation, so that package is more

> likely to receive updates. -- szermatt



[MisTTY]: http://github.com/szermatt/mistty



## INSTALLATION



Copy bash-completion.el into a directory that's on Emacs load-path.

You can do that manually, or by installing it from

[MELPA](https://melpa.org/#/getting-started).



### Shell completion



To enable bash completion in shell buffers as well as in command

prompts, such as the prompt started by `compile`, add the hook

`bash-completion-dynamic-complete` to

`shell-dynamic-complete-functions`.



For example:



```elisp

        (autoload 'bash-completion-dynamic-complete

          "bash-completion"

          "BASH completion hook")

        (add-hook 'shell-dynamic-complete-functions

          'bash-completion-dynamic-complete)

```



or simpler, but forces you to load bash-completion at startup:



```elisp

        (require 'bash-completion)

        (bash-completion-setup)

```



After that reload your .emacs (`M-x eval-buffer`) or restart.



When called from a bash shell buffer,

`bash-completion-dynamic-complete` communicates with the current shell

to reproduce, as closely as possible the normal bash auto-completion,

available on full terminals.



When called from non-shell buffers, such as the prompt of M-x compile,

`bash-completion-dynamic-complete` creates a separate bash process

just for doing completion. Such processes have the environment

variable `EMACS_BASH_COMPLETE` set to `t`, to help distinguish them

from normal shell processes.



### Completion at point



You can also use bash completion as an additional completion function

in any buffer that contains bash commands. To do that, add

`bash-completion-capf-nonexclusive` to the buffer-local

`completion-at-point-functions`. For example, you can setup bash

completion in `eshell-mode` by invoking



```elisp

(add-hook 'eshell-mode-hook

          (lambda ()

            (add-hook 'completion-at-point-functions

                      'bash-completion-capf-nonexclusive nil t)))

```



There is also a lower-level function

`bash-completion-dynamic-complete-nocomint` which allows you to

construct your own `completion-at-point` function.



```elisp

(bash-completion-dynamic-complete-nocomint COMP-START COMP-POS DYNAMIC-TABLE)

```



COMP-START is where the bash command starts --- it depends on the mode

of the calling buffer. In most cases, `line-beginning-position` works

because it uses `field` boundaries.



COMP-POS is usually the current position of the cursor.



When calling from `completion-at-point`, make sure to pass a non-nil

value to the DYNAMIC-TABLE argument so it returns a function instead

of a list of strings. This isn't just an optimization: returning a

function instead of a list tells Emacs it should avoids post-filtering

the results and possibly discarding useful completion from bash.



## TROUBLESHOOTING



If completion in a bash shell doesn't behave as you think it should, check

the following:



* Does bash behave differently when run outside of Emacs? If not, check

  your shell configuration.

* Call `M-x bash-completion-debug` and look at the `output-buffer`

  section. Does it  match the expected set of completion? If yes,

  it might be a display problem. Are you using a completion engine

  other than the default, such as ivy or helm? Try turning it off to

  confirm, then [file a bug](

    https://github.com/szermatt/emacs-bash-completion/issues/new).

* If all else fails, [file a bug](

  https://github.com/szermatt/emacs-bash-completion/issues/new). Please

  include the output of `M-x bash-completion-debug`, the command you're

  trying to use and the function or package providing completion for

  that command and where to download it.



## CONTRIBUTING



To report bugs, features, please open an [issue](

https://github.com/szermatt/emacs-bash-completion/issues/new). To ask 

questions or just for general comments, add a new [discussion](

https://github.com/szermatt/emacs-bash-completion/discussions). To 

contribute code or documentation, please open a [pull request](

https://github.com/szermatt/emacs-bash-completion/pulls).



See [CONTRIBUTING.md](CONTRIBUTING.md) for more details.



## COMPATIBILITY



bash-completion.el is known to work with Bash 4.2 and later and Bash

5, on Emacs, starting with version 25.3, under Linux and OSX.