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Matterhorn is a terminal client for the Mattermost chat system.

![](screenshots/screenshot-00.png)

# New Release Notifications

Get notified about new Matterhorn releases by following our Twitter account!

[https://twitter.com/matterhorn_chat](https://twitter.com/matterhorn_chat)

# Chat With the Developers

The Matterhorn developers hang out on the official Mattermost
pre-release server. Stop by to get support and say hello!

[https://pre-release.mattermost.com/core/channels/matterhorn](https://pre-release.mattermost.com/core/channels/matterhorn)

# Quick Start

We provide pre-built binary releases for some platforms. Please see the
release list to download a binary release for your platform that matches
your server version:

https://github.com/matterhorn-chat/matterhorn/releases

To run Matterhorn, unpack the binary release archive and run the
`matterhorn` binary within.

When you run Matterhorn you'll be prompted for your server information
and credentials. At present `matterhorn` supports only username/password
authentication.

Note: Version `ABBCC.X.Y` matches Mattermost server version `A.BB.CC`.
For example, if your Mattermost server version is `3.6.0` then you
would download matterhorn version `30600.2.4`. See [Our Versioning
Scheme](#our-versioning-scheme) for details.

# Configuring

For configuration options you have two choices:

* Interactive configuration entered on each program run
* Configuration via stored settings in a config file

The first option is useful when trying out the program because you can
get up and running without worrying about making a configuration. Once
you're ready to make your settings persistent, they can be added to
a configuration file. An example configuration file can be found at
`sample-config.ini`. Any settings omitted from the configuration will be
obtained interactively at startup.

When looking for configuration files, matterhorn will prefer
`config.ini` in the current working directory, but will look in the
typical XDG configuration directories (you'll probably want to use
`$HOME/.config/matterhorn/config.ini`) and as a last resort look for a
globally-accessible `/etc/matterhorn/config.ini`.

# Using the Client

The user interface has three main areas:

* Left: list of channels you're in, and list of users in your team and
  their statuses (`+` means online, `-` means away, `×` means Do Not
  Disturb, and an absent sigil means offline)
* Right: messages in the current channel
* Bottom: editing area for writing, editing, and replying to messages

You can use built-in keybindings or `/cmd`-style commands to operate
the client. To see available keybindings and commands, use the default
binding of `F1` or run the `/help` command. Keybindings may include
modifiers such as Control (indicated with a `C-` prefix) or Meta
(indicated with a `M-` prefix). If your keyboard has an `Alt` key, that
will work as `Meta`. If it does not, you may be able to configure your
terminal to provide `Meta` via other means (e.g. iTerm2 on OS X can be
configured to make the left Option key work as Meta). Keybindings can
be customized in the configuration file; see `/help keybindings` for
details.

To join a channel, use the `/join` command to choose from a list of
available channels. To create a channel, use `/create-channel`. To leave
a channel, use `/leave-channel`.

To create a private group chat amongst yourself and other users, use the
`/group-msg` command, e.g., `/group-msg user1 user2`.

To see the members in the current channel, use the `/members` command.

To send a message, type it into the editor and press Enter to send.
To send a multi-line message, toggle multi-line mode with the default
binding `M-e`. Markdown syntax is accepted.

To edit your current message in an external editor (`$EDITOR`), use the
default binding of `M-k`.

To preview the message you're about to send while you compose it (e.g.
to check on how your Markdown syntax will be rendered), toggle preview
mode with the default binding `M-p`.

To change channels, use `/focus` or one of the default bindings `C-n`
(next channel), `C-p` (previous channel), `C-g` (fast channel switch).

To directly message another user, use `/focus` or `C-g`.

`C-g` channel switching mode does a substring match of the input text on
the channel and usernames; metacharacters `^` and `$` at the beginning
or end of input, respectively, anchor the match in case of multiple
matches. The cursor in this mode is usable with `C-n` and `C-p`.

To switch to the channel you were in prior to the current channel, use
the default binding `M-s` (swap). The most recent channel is marked in
the channel list with a "`<`" indicator.

To switch to the next channel with unread messages, use the default
binding `M-a`.

To quickly show a list of URLs mentioned in the current channel and then
open one in your local browser, use the default binding of `C-o` and
configure the `urlOpenCommand` configuration setting.

To edit, delete, flag, or reply to a message, select a message with
the default binding of `C-s`. Use the default binding of `C-c` to
cancel these operations.

Messages that have been flagged can be viewed with either the `/flags`
command or `M-8`. This view allows you to select and unflag particular
messages, as well.

To enable spell-checking in the message editor, install Aspell and set
`enableAspell` to `True` in your configuration. To override Aspell's
choice of master dictionary, set the `aspellDictionary` option to the
name of the dictionary you'd like to use.

To attach a file to the post being edited, use the default binding of
`C-x`. The window that appears will let you browse the filesystem to
find a file to attach. In this window, `o` opens the selected file with
your URL open command to let you preview your choice, `Enter` enters the
selected directory or selects the current file for attachment, and arrow
keys change selection. Once you've attached a file, you'll see the text
`(1 attachment)` above your message editor. You can attach additional
files or remove existing attachments by pressing `C-x` again.

# Features

* Channel creation, deletion, and membership management commands
* Optimized channel-switching modes: `M-a`, `M-s`, and `C-g`
* Message posting, editing, replying, and deletion
* Markdown rendering
* Convenient URL-opening with local browser
* Secure password entry via external command (e.g. OSX keychain)
* Yank verbatim content from messages into the system clipboard
* Preview message rendering before sending
* Optional smart quoting for efficient Markdown entry
* Edit messages with `$EDITOR`
* Rebindable keys (see `/help keybindings`)
* Message editor with kill/yank buffer and readline-style keybindings
* Tab-completion of usernames, channel names, commands, and fence code
  block languages
* Support for attachment upload and download
* Spell-checking via Aspell
* Syntax highlighting of fenced code blocks in messages (works best in
  256-color terminals)
* Flagging and unflagging of posts, which are then viewable with `M-8`
  or `/flags`
* Support for SOCKS 4 and 5 proxies via the `ALL_PROXY`, `HTTP_PROXY`,
  and `HTTPS_PROXY` environment variables. (Plain HTTP proxies are not
  yet supported.)
* Multiple color themes with color theme customization support
* Custom notifications via notification scripts (see the
  `activityNotifyCommand` configuration setting).

# Spell Checking Support

Matterhorn uses `aspell` to perform spell-checking of your message
input. To use this feature:

 * Install `aspell` and ensure that your installation includes
   dictionaries corresponding to your `LANG` setting. To check this, ask
   `aspell` to check some input:
   ```
   $ echo stuff | aspell -a
   Error: No word lists can be found for the language "en".
   $ echo $LANG
   en_US
   ```
   If Aspell succeeds, the output will look like this:
   ```
   @(#) International Ispell Version 3.1.20 (but really Aspell 0.60.6.1)
   *
   ```
 * Set `enableAspell` to `True` in your `config.ini`
 * Enter any message input in the message editor in `matterhorn`. After
   a short delay after you stop typing, misspelled words will turn red.

# Building

To build Matterhorn, you'll need an appropriate `ghc`/`cabal`
installation. We currently build on GHC 8.4. We suggest you use a binary
release if possible.

`matterhorn` is built by running the following commands:

```
$ git pull
$ git submodule update --init
$ ./build.sh
```

# Our Versioning Scheme

Matterhorn version strings will be of the form `ABBCC.X.Y` where ABBCC
corresponds to the Mattermost server version supported by the release.
For example, if a release supports Mattermost server version 1.2.3, the
ABBCC portion of the `matterhorn` version will be `10203`. The `X.Y`
portion of the version corresponds to our own version namespace for the
package. If the server version changes, `X.Y` SHOULD be `0.0`. Otherwise
the first component should increment if the package undergoes major code
changes or functionality changes. The second component alone should
change only if the package undergoes security fixes or other bug fixes.

# Contributing

If you decide to contribute, that's great! Here are some guidelines you
should consider to make submitting patches easier for all concerned:

 - If you want to take on big things, let's have a design/vision
   discussion before you start coding. Create a GitHub issue and we can
   use that as the place to hash things out. We'll be interested to
   discuss any usability / UI, performance, or compatibility issues.
 - Please make changes consistent with the conventions already used in
   the codebase.
 - We follow a few development practices to support our project and it
   helps when contributors are aware of these. Please see `PRACTICES.md`
   for more information.

# Frequently Asked Questions

* Q: Does matterhorn support Gitlab authentication?
* A: No. But we would be happy to work with contributors who are
  interested in investigating what this would take and/or implementing
  it.  See the Contributing section for details.

* Q: I enabled italicized text in my theme configuration. Why doesn't it
  work?
* A: Most terminfo files for typical terminal configurations do not
  provide support for italicized text. If your terminal emulator
  supports italics, you must enable it in your terminfo database in
  order to use it in Matterhorn. For more information, see these links:
  * http://www.nerdyweekly.com/posts/enable-italic-text-vim-tmux-gnome-terminal/
  * https://medium.com/@dubistkomisch/how-to-actually-get-italics-and-true-colour-to-work-in-iterm-tmux-vim-9ebe55ebc2be
  * https://github.com/tmux/tmux/blob/2.1/FAQ#L355-L383