Add programmable bash completion to Emacs shell-mode
bash-completion.el defines dynamic completion hooks for shell-mode and shell-command prompts that is based on bash completion.
Bash completion for Emacs:
A simpler and more complete alternative to bash-completion.el is to run a bash shell in a buffer in term mode (
M-x ansi-term). Unfortunately, many Emacs editing features are not available when running in term mode. Also, term mode is not available in shell-command prompts.
Copy bash-completion.el into a directory that's on Emacs load-path. You can do that manually, or by installing it from MELPA.
To enable bash completion in shell buffers as well as in command prompts, such as the prompt started by
compile, add the hook
(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:
(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-completecommunicates 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-completecreates a separate bash process just for doing completion. Such processes have the environment variable
t, to help distinguish them from normal shell processes.
Additionally, you can enable bash completion in any buffer that contains bash commands. To do that, call
elisp (bash-completion-dynamic-complete-nocomint COMP-START COMP-POS DYNAMIC-TABLE)from a function added to
The trickiest part is setting COMP-START to where the bash command starts; It depends on the mode of the calling buffer and might, in some cases, span multiple lines.
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.
For example, here's a function to to do bash completion from an eshell buffer. To try it out, add the function below to your init file and bind
bash-completion-from-eshellto a custom shortcut.
(defun bash-completion-from-eshell () (interactive) (let ((completion-at-point-functions '(bash-completion-eshell-capf))) (completion-at-point)))
(defun bash-completion-eshell-capf () (bash-completion-dynamic-complete-nocomint (save-excursion (eshell-bol) (point)) (point) t))
If completion in a bash shell doesn't behave as you think it should, check the following:
sudo? If yes, call
bash-completion-refreshto configure the new bash process.
M-x bash-completion-debugand look at the completion table at the bottom. Does it match your expectation? If not, call
M-x bash-completion-refreshto refresh the copy of the completion table kept by Emacs, or if you're in a
M-x compileprompt, call
M-x bash-completion-reset-all, then try again.
M-x bash-completion-debug, does the
output-buffersection 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
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.
See CONTRIBUTING.md for more details.
bash-completion.el is known to work with Bash 3, 4 and 5, on Emacs, starting with version 24.3, under Linux and OSX. It does not work on XEmacs.