momomo5717/helm

Emacs incremental completion and selection narrowing framework

Emacs-helm

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Table of Contents

• Introduction
• Requirements
• Getting Started
  • Quick install from git
  • Install from Emacs packaging system
  • Debian and Ubuntu
  • Installing just the helm-core package
  • Warning about alternate installation methods
  • Configuration
  • Basic usage
  • Advanced usage
    • Creating custom helm sources
    • Fuzzy matching
    • Autoresize
• Helm Applications
• Recommended Helm extensions
• Known issues
• Contributors
• Bugs & Improvements
• Getting help

Introduction

Helm is an Emacs framework for incremental completions and narrowing selections. It helps to rapidly complete file names, buffer names, or any other Emacs interactions requiring selecting an item from a list of possible choices.

Helm is a fork of anything.el, which was originally written by Tamas Patrovic and can be considered to be its successor. Helm cleans the legacy code that is leaner, modular, and unchained from constraints of backward compatibility.

Requirements

Helm requires Emacs-24.3 or later versions.

Helm installs async package as a dependency when Helm is installed using MELPA.

Helm installation from the git source repository does not include async. The async package is recommended for smooth asynchronous file and dired operations in Helm.

Getting Started

Quick install from git

1. Clone the helm repository to some directory:

```elisp
$ git clone https://github.com/emacs-helm/helm.git /path/to/helm/directory
```

2. Clone the async repository to some directory (facultative)

```elisp
$ git clone https://github.com/jwiegley/emacs-async.git /path/to/async/directory
```

3. Run make from the helm directory.

4. Add to .emacs.el (or equivalent):

```elisp
;; If async is installed
(add-to-list 'load-path "/path/to/async/directory")

(add-to-list 'load-path "/path/to/helm/directory")
(require 'helm-config)
```

NOTE: Installing helm using git and make is the safest way.

To quickly run helm, launch this script from helm directory:

./emacs-helm.sh

Also use the same script above for bug reporting.

NOTE: This script does not work on Windows systems.

Install from Emacs packaging system

Helm can also be installed from MELPA repository at http://melpa.org/. No further configuration is necessary to run helm other than perhaps a one-line entry in the Emacs init file:

(require 'helm-config)

WARNING: Helm upgrades from MELPA repository encountered errors because of the way package.el fetched and compiled updates for existing packages. To get around these errors, Helm adds Async as a dependency package install. Async forces compilation in a clean environment, which solves those compilation errors. Since async has other benefits as well, both for Helm and other packages, we recommend installing async even for Helm installs using git. See FAQ for details.

Note: Restart Emacs for Helm updates from MELPA repositories to take effect.

Note to Linux Distributions Maintainers

Only the extensions in the github emacs-helm repository are supported.

Debian and Ubuntu

Users of Debian 9 or later or Ubuntu 16.04 or later may simply apt-get install elpa-helm (or apt-get install elpa-helm-core; see below).

Installing just the helm-core package

helm-core package is available on MELPA for third party packages that depend on helm libraries. These packages should require helm as follows:

 (require 'helm)

Requiring helm builds and runs helm code necessary for multiple regexp and fuzzy matching. See helm wiki for details.

Warning about alternate installation methods

Installation methods that circumvent helm-config are known to fail if the careful safeguards are not implemented in the hacks.

Configuration

For minimal helm configuration, run the start-up script ./emacs-helm.sh and then see the file /tmp/helm-cfg.el.

The full configuration I (the helm maintainer) use is here.

Also see helm customizable variables with the customize interface. Enabling helm-mode will enable helm for many features of emacs requiring completions.

For pre-configured Emacs installs, such as Emacs Prelude, helm is built-in with no additional configuration steps necessary for using helm.

Basic usage

M-x helm-M-x RET helm- lists helm commands ready for narrowing and selecting.

To bind to M-x:

(global-set-key (kbd "M-x") 'helm-M-x)

• IMPORTANT:

In any helm session (after helm-M-x or helm- command)

C-h m pops a general info buffer about helm

C-c ? pops a special info buffer of the current helm command

Not all helm commands have specialized info buffers. Look for C-c ? in the mode-line. C-h m is shown for any command that does not have a specialized info buffer.

Use these embedded Info screens first before reporting bugs.

M-x helm-mode to enable helm completion for common Emacs commands (e.g M-x, C-x C-f, etc...). Note that the helm functionality enabled through helm-mode comes from a generic implementation and does not include all helm features available through equivalent helm-specific commands. For example, helm-M-x has more features than helm completion through M-x.

To make helm-mode start with Emacs init file:

(helm-mode 1)

To discover helm commands, look at helm menu item in Emacs menu.

Another way to discover helm commands: run the shell script: ./emacs-helm.sh and then look in the scratch buffer. emacs-helm.sh accepts emacs command line options. emacs-helm.sh -h opens an Info screen with more details.

Advanced usage

Helm contains many features, some of which are easier to follow visually. Here is a demo of helm-buffers-list used with helm-moccur. Demo starts with Eval: START in the minibuffer.

• Regexp *C selects the C buffers. *Tcl in the demo selects TCL buffers, then with *C switches back to C buffers.
• For buffers containing the string "crash", the demo adds a space, then the pattern @crash.
• Matching buffers are then handed over to helm-moccur - moccur with its own Helm interface. The demo shows switching to a single file, kexec.c. Multiple selections can be made with C-SPC. M-a selects all.
• Adding characters to the pattern gradually filters (narrows) the available candidates. By adding memory, the buffers shown now include those buffers with "crash" and "memory".

With more pattern matching, candidates are narrowed down from the initial 253 buffers to 12 as shown in the modeline.

Helm guide and Helm Wiki provide additional details.

Creating custom helm sources

An example:

(helm :sources (helm-build-sync-source "test"
                 :candidates '(foo foa fob bar baz)
                 :fuzzy-match t)
      :buffer "*helm test*")

The candidates list may be replaced by a function that produces a list. See (helm wiki) for details.

Fuzzy matching

Helm's built-in fuzzy matcher is activated for some commands. Helm's fuzzy matching is disabled by default. Currently these commands support fuzzy matching:

• helm-recentf: set helm-recentf-fuzzy-match to t.
• helm-mini: set helm-buffers-fuzzy-matching and helm-recentf-fuzzy-match to t.
• helm-buffers-list: set helm-buffers-fuzzy-matching to t.
• helm-find-files: fuzzy matching enabled by default.
• helm-locate: set helm-locate-fuzzy-match to t.
• helm-M-x: set helm-M-x-fuzzy-match to t.
• helm-semantic: set helm-semantic-fuzzy-match to t.
• helm-imenu: set helm-imenu-fuzzy-match to t.
• helm-apropos: set helm-apropos-fuzzy-match to t.
• helm-lisp-completion-at-point: set helm-lisp-fuzzy-completion to t.

To globally enable fuzzy matching for helm-mode:

• set helm-mode-fuzzy-match to t.
• set helm-completion-in-region-fuzzy-match to t.

IMPORTANT: For faster fuzzy matching, set helm-candidate-number-limit to 100 or less. Default is 100.

Autoresize

To re-size the completion window based on number of candidates:

(helm-autoresize-mode 1)

Adjust minimum and maximum height of completion window using:

• helm-autoresize-max-height
• helm-autoresize-min-height

40 is the default value of helm-autoresize-max-height, which sets the completion window height to 40% of the fame height. helm-autoresize-min-height specifies the minimum height that the completion window cannot shrink to.

For a fixed window size, set helm-autoresize-min-height equal to helm-autoresize-max-height.

Helm Applications

These are popular applications developed using helm completion and narrowing framework. They are available for individual installs through the Emacs package manager. This list is not exhaustive.

• helm-mode: turns on helm completions for most standard emacs completions. Helm provides even more optimized helm completions for some commands in helm-mode. Prefer these natively optimized versions over the ones in helm-mode.
• helm-find-files: one command that handles all the files related commands (bind to C-x C-f).
• helm-buffers-list: provides enhanced buffers listing.
• helm-browse-project: handles project files and buffers; defaults to current directory; works with helm-find-files; recommended with helm-ls-git, helm-ls-hg and helm-ls-svn for a better handling of version control files.
• helm-dabbrev: enhanced dabbrev implementation with helm completion; does not use emacs code.
• helm-moccur: enhanced occur for one or more buffers; launch from helm-buffers-list or current-buffer.
• helm-M-x: enhanced execute-extended-command (bind to M-x).
• helm-imenu and helm-imenu-in-all-buffers: provide imenus for current or all buffers.
• helm-etags-select: enhanced etags with helm-completion; usable everywhere with helm-find-files.
• helm-apropos: enhanced apropos for functions and variables that C-h commands provide.
• Grep: launch from any helm file commands; supports back-ends grep, ack-grep, git-grep, ag and custom implementation of pt.
• helm-gid: Helm interface for gid from id-utils.
• helm-show-kill-ring: A helm browser for kill ring.
• helm-all-mark-rings: A helm browser for mark ring; retrieves last positions in buffers.
• helm-filtered-bookmarks: enhanced browser for bookmarks.
• helm-list-elisp-packages: enhanced browser for elisp package management.

Recommended Helm extensions

• helm-ls-git
• helm-ls-hg
• helm-descbinds
• helm-firefox

Warning Helm development has sparked quite a few extensions, many of which duplicate features already included in helm. Some of these packages (about 20 at last count in the MELPA repository) are either deprecated or unmaintained. Moreover, many remain out-of-sync with helm core development cycles causing incompatibilities. To avoid helm problems or unstable emacs, please look for comparable features within helm and emacs-helm before installing such extensions.

Known issues

The Helm project has a currant unresolved issue list. Please feel free to fix any of them; send a pull request.

Contributors

The Helm project maintains a list of contributors.

Bugs & Improvements

The Helm Team welcomes bug reports and suggestions. Note that not all bugs when using Helm are due to Helm. Because of the way Helm interacts with many Emacs features, bugs may be related to Emacs itself.

One way to ascertain that the bugs are helm-related, recreate the error either by using Emacs -Q or by running the included package script ./emacs-helm.sh located in the helm directory.

Getting help

Helm Wiki and emacs-helm Google group are two readily available locations.

Cheers,
The Helm Team