/emacs-libvterm

Emacs libvterm integration

Primary LanguageCGNU General Public License v3.0GPL-3.0

MELPA

Introduction

Emacs-libvterm (vterm) is fully-fledged terminal emulator inside GNU Emacs based on libvterm, a C library. As a result of using compiled code (instead of elisp), emacs-libvterm is fully capable, fast, and it can seamlessly handle large outputs.

Warning

This package is in active development and, while being stable enough to be used as a daily-driver, it is currently in early alpha stage. This means that occasionally the public interface will change (for example names of options or functions). A list of recent breaking changes is in appendix. Moreover, emacs-libvterm deals directly with some low-level operations, hence, bugs in the code can lead to segmentation faults and crashes. If that happens, please report the problem.

Installation

Requirements

Before installing emacs-libvterm, you need to make sure you have installed

  1. GNU Emacs (>= 25.1) with module support. You can check that, by verifying that module-file-suffix is not nil.
  2. cmake (>= 3.11)
  3. libtool-bin (related issues: #66 #85)
  4. OPTIONAL: libvterm. This library can be found in the official repositories of most distributions (e.g., Arch, Debian, Fedora, Gentoo, openSUSE, Ubuntu). If not available, it will be downloaded during the compilation process.

From MELPA

vterm is available on MELPA, and it can be installed as a normal package. If the requirements are satisfied (mainly, Emacs was built with support for modules), vterm will compile the module the first time it is run. This is the recommended way to install vterm.

vterm can be install from MELPA with use-package by adding the following lines to your init.el:

(use-package vterm
    :ensure t)

To take full advantage of the capabilities of vterm, you should configure your shell too. Read about this in the section shell-side configuration.

Manual installation

Clone the repository:

git clone https://github.com/akermu/emacs-libvterm.git

In case you want to use the version of libvterm already installed on your system, change cmake .. with cmake -DUSE_SYSTEM_LIBVTERM=yes .. in the following instructions. If -DUSE_SYSTEM_LIBVTERM is not explicitly set to yes (or if it is set to no), emacs-libvterm will download the latest version available of libvterm (from here), compile it, and use it.

Build the module with:

cd emacs-libvterm
mkdir -p build
cd build
cmake ..
make

And add this to your init.el:

(add-to-list 'load-path "path/to/emacs-libvterm")
(require 'vterm)

Or, with use-package:

(use-package vterm
  :load-path  "path/to/emacs-libvterm/")

vterm and Ubuntu

Using vterm on Ubuntu requires additional steps. The latest LTS version (18.04) ships with a version of CMake that is too old for vterm and GNU Emacs is not compiled with support for dynamical module loading.

It is possible to install GNU Emacs with module support from Kevin Kelley's PPA. The binary in Ubuntu Emacs Lisp PPA is currently broken and leads to segmentation faults (see #185). In case Emacs is already on the system, you need to purge it before proceeding with the following commands.

sudo add-apt-repository ppa:kelleyk/emacs
sudo apt update
sudo apt-get install emacs26

A way to install a recent version of CMake (>= 3.11) is with linuxbrew.

brew install cmake

In some cases, /bin/sh needs to be relinked to /bin/bash for the compilation to work (see, #216).

Pull requests to improve support for Ubuntu are welcome (e.g., simplyfing the installation).

GNU Guix

vterm and its dependencies are available in GNU Guix as emacs-vterm. The package can be installed with guix package -i emacs-vterm.

Shell-side configuration

Some of the most useful features in vterm (e.g., directory-tracking and prompt-tracking or message passing) require shell-side configurations. The main goal of these additional functions is to enable the shell to send information to vterm via properly escaped sequences. A function that helps in this task, vterm_printf, is defined below. This function is widely used throughout this readme.

For bash or zsh, put this in your .zshrc or .bashrc

function vterm_printf(){
    if [ -n "$TMUX" ]; then
        # Tell tmux to pass the escape sequences through
        # (Source: http://permalink.gmane.org/gmane.comp.terminal-emulators.tmux.user/1324)
        printf "\ePtmux;\e\e]%s\007\e\\" "$1"
    elif [ "${TERM%%-*}" = "screen" ]; then
        # GNU screen (screen, screen-256color, screen-256color-bce)
        printf "\eP\e]%s\007\e\\" "$1"
    else
        printf "\e]%s\e\\" "$1"
    fi
}

For fish put this in your ~/.config/fish/config.fish:

function vterm_printf;
    if [ -n "$TMUX" ]
        # tell tmux to pass the escape sequences through
        # (Source: http://permalink.gmane.org/gmane.comp.terminal-emulators.tmux.user/1324)
        printf "\ePtmux;\e\e]%s\007\e\\" "$argv"
    else if string match -q -- "screen*" "$TERM"
        # GNU screen (screen, screen-256color, screen-256color-bce)
        printf "\eP\e]%s\007\e\\" "$argv"
    else
        printf "\e]%s\e\\" "$argv"
    end
end

Debugging and testing

If you have successfully built the module, you can test it by executing the following command in the build directory:

make run

Usage

vterm

Open a terminal in the current window.

vterm-other-window

Open a terminal in another window.

vterm-copy-mode

When you enable vterm-copy-mode, the terminal buffer behaves like a normal read-only text buffer: you can search, copy text, etc. The default keybinding to toggle vterm-copy-mode is C-c C-t. When a region is selected, it is possible to copy the text and leave vterm-copy-mode with the enter key.

If no region is selected when the enter key is pressed it will copy the current line from start to end. If vterm-copy-exclude-prompt is true it will skip the prompt and not include it in the copy.

vterm-clear-scrollback

vterm-clear-scrollback does exactly what the name suggests: it clears the current buffer from the data that it is not currently visible. vterm-clear-scrollback is bound to C-c C-l. This function is typically used with the clear function provided by the shell to clear both screen and scrollback. In order to achieve this behavior, you need to add a new shell alias.

For zsh, put this in your .zshrc:

if [[ "$INSIDE_EMACS" = 'vterm' ]]; then
    alias clear='vterm_printf "51;Evterm-clear-scrollback";tput clear'
fi

For bash, put this in your .bashrc:

if [[ "$INSIDE_EMACS" = 'vterm' ]]; then
    function clear(){
        vterm_printf "51;Evterm-clear-scrollback";
        tput clear;
    }
fi

These aliases take advantage of the fact that vterm can execute elisp commands, as explained below.

If it possible to automatically clear the scrollback when the screen is cleared by setting the variable vterm-clear-scrollback-when-clearing: When vterm-clear-scrollback-when-clearing is non nil, C-l clears both the screen and the scrollback. When is nil, C-l only clears the screen. The opposite behavior can be achieved by using the universal prefix (ie, calling C-u C-l).

Customization

vterm-shell

Shell to run in a new vterm. It defaults to $SHELL.

vterm-term-environment-variable

Value for the TERM environment variable. It defaults to xterm-256color. If eterm-256color is installed, setting vterm-term-environment-variable to eterm-color improves the rendering of colors in some systems.

vterm-kill-buffer-on-exit

If set to t, buffers are killed when the associated process is terminated (for example, by logging out the shell).

vterm-module-cmake-args

Compilation flags and arguments to be given to CMake when compiling the module. This string is directly passed to CMake, so it uses the same syntax. At the moment, it main use is for compiling vterm using the system libvterm instead of the one downloaded from GitHub. You can find all the arguments and flags available with cmake -LA in the build directory.

vterm-copy-exclude-prompt

Controls whether or not to exclude the prompt when copying a line in vterm-copy-mode. Using the universal prefix before calling vterm-copy-mode-done will invert the value for that call, allowing you to temporarily override the setting.

The variable vterm-copy-use-vterm-prompt determines whether to use the vterm prompt tracking, if false it use the regexp in vterm-copy-prompt-regexp to search for the prompt. If not found, it copies the whole line.

vterm-buffer-name-string

When vterm-buffer-name-string is not nil, vterm renames automatically its own buffers with vterm-buffer-name-string. This string can contain the character %s, which is substituted with the title (as defined by the shell, see below). A possible value for vterm-buffer-name-string is vterm %s, according to which all the vterm buffers will be named "vterm TITLE".

This requires some shell-side configuration to print the title. For example to set the name "HOSTNAME:PWD", use can you the following:

For zsh

autoload -U add-zsh-hook
add-zsh-hook -Uz chpwd (){ print -Pn "\e]2;%m:%2~\a" }

For bash,

PROMPT_COMMAND='echo -ne "\033]0;\h:\w\007"'

For fish,

function fish_title
    hostname
    echo ":"
    pwd
end

See zsh and bash and (fish documentations)[https://fishshell.com/docs/current/#programmable-title].

vterm-always-compile-module

Vterm needs vterm-module to work. This can be compiled externally, or vterm will ask the user whether to build the module when vterm is first called. To avoid this question and always compile the module, set vterm-always-compile-module to t.

Keybindings

If you want a key to be sent to the terminal, bind it to vterm--self-insert, or remove it from vterm-mode-map. By default, vterm.el binds most of the C-<char> and M-<char> keys, <f1> through <f12> and some special keys like <backspace> and <return>. Sending a keyboard interrupt is bound to C-c C-c.

Fonts

If you would like to change the font or face used in a vterm, use the following code:

(add-hook 'vterm-mode-hook
          (lambda ()
            (set (make-local-variable 'buffer-face-mode-face) 'fixed-pitch)
                 (buffer-face-mode t)))

The above would change change the font in vterm buffers to a mono-spaced font (the fixed-pitch face) if your default font in Emacs is a proportional font.

Colors

Set the :foreground and :background attributes of the following faces to a color you like. The :foreground is ansi color 0-7, the :background attribute is ansi color 8-15.

  • vterm-color-default
  • vterm-color-black
  • vterm-color-red
  • vterm-color-green
  • vterm-color-yellow
  • vterm-color-blue
  • vterm-color-magenta
  • vterm-color-cyan
  • vterm-color-white

Directory tracking and Prompt tracking

vterm supports directory tracking. If this feature is enabled, the default directory in Emacs and the current working directory in vterm are synced. As a result, interactive functions that ask for a path or a file (e.g., dired or find-file) will do so starting from the current location.

And vterm supports prompt tracking. If this feature is enabled, Emacs knows where the prompt ends, you needn't customize term-prompt-regexp any more. Then you can use vterm-next-prompt and vterm-previous-prompt moving to end of next/previous prompt. The default keybinding is C-c C-n and C-c C-p.

And vterm-beginning-of-line would move the point to the first character after the shell prompt on this line. If the point is already there, move to the beginning of the line. The default keybinding is C-a in vterm-copy-mode.

And vterm--at-prompt-p would check whether the cursor is at the point just after the shell prompt.

Directory tracking and Prompt tracking requires some configuration, as the shell has to be instructed to share the relevant information with Emacs. The following pieces of code assume that you have the function vterm_printf as defined in section shell-side configuration.

For zsh, put this at the end of your .zshrc:

vterm_prompt_end() {
    vterm_printf "51;A$(whoami)@$(hostname):$(pwd)";
}
setopt PROMPT_SUBST
PROMPT=$PROMPT'%{$(vterm_prompt_end)%}'

For bash, put this at the end of your .bashrc:

vterm_prompt_end(){
    vterm_printf "51;A$(whoami)@$(hostname):$(pwd)"
}
PS1=$PS1'\[$(vterm_prompt_end)\]'

For fish, put this in your ~/.config/fish/config.fish:

function vterm_prompt_end;
    vterm_printf '51;A'(whoami)'@'(hostname)':'(pwd)
end
functions -c fish_prompt vterm_old_fish_prompt
function fish_prompt --description 'Write out the prompt; do not replace this. Instead, put this at end of your file.'
    # Remove the trailing newline from the original prompt. This is done
    # using the string builtin from fish, but to make sure any escape codes
    # are correctly interpreted, use %b for printf.
    printf "%b" (string join "\n" (vterm_old_fish_prompt))
    vterm_prompt_end
end

Directory tracking works on remote servers too. In case the hostname of your remote machine does not match the actual hostname needed to connect to that server, change $(hostname) with the correct one. For example, if the correct hostname is foo and the username is bar, you should have something like

HOSTNAME=foo
USER=baz
vterm_printf "51;A$USER@$HOSTNAME:$(pwd)"

Message passing

vterm can read and execute commands. At the moment, a command is passed by providing a specific escape sequence. For example, to evaluate

(message "Hello!")

use

printf "\e]51;Emessage \"Hello\!\"\e\\"

# or
vterm_printf "51;Emessage \"Hello\!\""

The commands that are understood are defined in the setting vterm-eval-cmds.

As split-string-and-unquote is used the parse the passed string, double quotes and backslashes need to be escaped via backslash. For instance, bash can replace strings internally.

vterm_cmd() {
    if [ -n "$TMUX" ]; then
        # tell tmux to pass the escape sequences through
        # (Source: http://permalink.gmane.org/gmane.comp.terminal-emulators.tmux.user/1324)
        printf "\ePtmux;\e\e]51;E"
    elif [ "${TERM%%-*}" = "screen" ]; then
        # GNU screen (screen, screen-256color, screen-256color-bce)
        printf "\eP\e]51;E"
    else
        printf "\e]51;E"
    fi

    printf "\e]51;E"
    local r
    while [[ $# -gt 0 ]]; do
        r="${1//\\/\\\\}"
        r="${r//\"/\\\"}"
        printf '"%s" ' "$r"
        shift
    done
    if [ -n "$TMUX" ]; then
        # tell tmux to pass the escape sequences through
        # (Source: http://permalink.gmane.org/gmane.comp.terminal-emulators.tmux.user/1324)
        printf "\007\e\\"
    elif [ "${TERM%%-*}" = "screen" ]; then
        # GNU screen (screen, screen-256color, screen-256color-bce)
        printf "\007\e\\"
    else
        printf "\e\\"
    fi
}

However if you are using dash and need a pure POSIX implementation:

vterm_cmd() {
    if [ -n "$TMUX" ]; then
        # tell tmux to pass the escape sequences through
        # (Source: http://permalink.gmane.org/gmane.comp.terminal-emulators.tmux.user/1324)
        printf "\ePtmux;\e\e]51;E"
    elif [ "${TERM%%-*}" = "screen" ]; then
        # GNU screen (screen, screen-256color, screen-256color-bce)
        printf "\eP\e]51;E"
    else
        printf "\e]51;E"
    fi
    while [ $# -gt 0 ]; do
        printf '"%s" ' "$(printf "%s" "$1" | sed -e 's|\\|\\\\|g' -e 's|"|\\"|g')"
        shift
    done
    if [ -n "$TMUX" ]; then
        # tell tmux to pass the escape sequences through
        # (Source: http://permalink.gmane.org/gmane.comp.terminal-emulators.tmux.user/1324)
        printf "\007\e\\"
    elif [ "${TERM%%-*}" = "screen" ]; then
        # GNU screen (screen, screen-256color, screen-256color-bce)
        printf "\007\e\\"
    else
        printf "\e\\"
    fi
}

Now we can write shell functions to call the ones defined in vterm-eval-cmds.

find_file() {
    vterm_cmd find-file "$(realpath "$@")"
}

say() {
    vterm_cmd message "%s" "$*"
}

This can be used inside vterm as

find_file name_of_file_in_local_directory

As an example, say you like having files opened below the current window. You could add the command to do it on the lisp side like so:

(push (list "find-file-below"
            (lambda (path)
              (if-let* ((buf (find-file-noselect path))
                        (window (display-buffer-below-selected buf nil)))
                  (select-window window)
                (message "Failed to open file: %s" path))))
      vterm-eval-cmds)

Then add the command in your .bashrc file.

open_file_below() {
    vterm_cmd find-file-below "$(realpath "$@")"
}

Then you can open any file from inside your shell.

open_file_below ~/Documents

Frequently Asked Questions and Problems

<C-backspace> doesn't kill previous word.

This can be fixed by rebinding the key to what C-w does:

(define-key vterm-mode-map (kbd "<C-backspace>")
    (lambda () (interactive) (vterm-send-key (kbd "C-w"))))

counsel-yank-pop doesn't work.

Add this piece of code to your configuration file to make counsel use the correct function to yank in vterm buffers.

(defun vterm-counsel-yank-pop-action (orig-fun &rest args)
  (if (equal major-mode 'vterm-mode)
      (let ((inhibit-read-only t)
            (yank-undo-function (lambda (_start _end) (vterm-undo))))
        (cl-letf (((symbol-function 'insert-for-yank)
               (lambda (str) (vterm-send-string str t))))
            (apply orig-fun args)))
    (apply orig-fun args)))

(advice-add 'counsel-yank-pop-action :around #'vterm-counsel-yank-pop-action)

Related packages

Appendix

Breaking changes

  • vterm-clear-scrollback was renamed to vterm-clear-scrollback-when-clearning.
  • vterm-set-title-functions was removed. In its place, there is a new custom option vterm-buffer-name-string. See vterm-buffer-name-string for documentation.