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.
This package is in active development and, while being stable enough to be used as a daily-driver, it is currently in 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 can lead to segmentation faults and crashes. If that happens, please report the problem.
The short answer is: unparalleled performance and compatibility with standard command-line tools.
For the long answer, let us discuss the differences between eshell, shell,
term and vterm:
eshell: it is a shell completely implemented in Emacs Lisp. It is well-integrated in Emacs and it runs on Windows. It does not support command line tools that require terminal manipulation capabilities (e.g.,ncdu,nmtui, ...).shell: it interfaces with a standard shell (e.g.,bash). It reads an input from Emacs, sends it to the shell, and reports back the output from the shell. As such, likeeshell, it does not support interactive commands, especially those that directly handle how the output should be displayed (e.g.,htop).term: it is a terminal emulator written in elisp.termruns a shell (similarly to other terminal emulators like Gnome Terminal) and programs can directly manipulate the output using escape codes. Hence, many interactive applications (like the one aforementioned) work withterm. However,termandansi-termdo not implement all the escapes codes needed, so some programs do not work properly. Moreover,termhas inferior performance compared to standalone terminals, especially with large bursts of output.vterm: liketermit is a terminal emulator. Unliketerm, the core ofvtermis an external library written in C,libvterm. For this reason,vtermoutperformstermand has a nearly universal compatibility with terminal applications.
Vterm is not for you if you are using Windows, or if you cannot set up Emacs with support for modules. Otherwise, you should try vterm, as it provides a superior terminal experience in Emacs.
Using vterm is like using Gnome Terminal inside Emacs: Vterm is fully-featured
and fast, but is not as well integrated in Emacs as eshell (yet), so some of
the editing keybinding you are used to using may not work. For example,
evil-mode is currently not supported (though, users can enable VI emulation in
their shells). This is because keys are sent directly to the shell. We are
constantly working to improve this.
Before installing emacs-libvterm, you need to make sure you have installed
- GNU Emacs (>= 25.1) with module
support.
You can check that, by verifying that
module-file-suffixis notnil. - cmake (>= 3.11)
- libtool-bin (related issues: #66 #85)
- OPTIONAL: libvterm (>= 0.1). This
library can be found in the official repositories of most distributions
(e.g., Arch, Debian, Fedora, Gentoo, openSUSE, Ubuntu). Typical names are
libvterm(Arch, Fedora, Gentoo, openSUSE), orlibvterm-dev(Debian, Ubuntu). If not available,libvtermwill be downloaded during the compilation process. Some distributions (e.g. Ubuntu < 20.04, Debian Stable) have versions oflibvtermthat are too old. If you find compilation errors related toVTERM_COLOR, you should not use your system libvterm. See FAQ for more details.
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.
Clone the repository:
git clone https://github.com/akermu/emacs-libvterm.gitBy default, vterm will try to find if libvterm is installed. If it is not found,
emacs-libvterm will download the latest version available of libvterm (from
here), compile it, and use it. If you
always want to use the vendored version as opposed to the one on you system, set
USE_SYSTEM_LIBVTERM to no. To do this, change cmake .. with cmake -DUSE_SYSTEM_LIBVTERM=no .. in the following instructions.
Build the module with:
cd emacs-libvterm
mkdir -p build
cd build
cmake ..
makeAnd 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/")Using vterm on Ubuntu requires additional steps. The latest LTS version
(20.04) ships without CMake installed and Emacs27 is not yet available from Ubuntu's package repository.
The basic steps for getting vterm to work on Ubuntu 20.04 are:
- Ensure Emacs27 is installed
- Install cmake, libtool, and libtool-bin
There are a few options for installing Emacs27 on Ubuntu 20.04:
- Compile Emacs27 from source
- Install Emacs27 from Snap
- Install Emacs27 from Kevin Kelley's PPA
In any case, if you have an older Emacs version you will need to purge it before proceeding:
sudo apt --purge remove emacs
sudo apt autoremovesudo add-apt-repository ppa:kelleyk/emacs
sudo apt install emacs27Errors were encountered while processing:
/tmp/apt-dpkg-install-RVK8CA/064-emacs27-common_27.1~1.git86d8d76aa3-kk2+20.04_all.debrun
sudo apt --purge remove emacs-common
sudo apt --fix-broken installI hesitate to include SNAP here, because I ran into a number of GTK Theme parsing errors, and Fontconfig errors when I tested it, and reverted to installing from Kevin Kelley's PPA. YMMV
sudo snap install emacs --classicIn Ubuntu 20.04 CMake (v3.16.3-1ubuntu1) and Libtool can be installed with
sudo apt install cmake
sudo apt install libtool
sudo apt install libtool-binUsing vterm on Ubuntu 18.04 requires additional steps.
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 emacs26A way to install a recent version of CMake (>= 3.11) is with linuxbrew.
brew install cmakeIn 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., simplifying the installation).
Some releases of Ubuntu (e.g., 18.04) ship with a old version of libvterm that can lead to compilation errors. If you have this problem, see the FAQ for a solution.
vterm and its dependencies are available in GNU Guix as
emacs-vterm.
The package can be installed with guix package -i emacs-vterm.
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
vterm_printf(){
if [ -n "$TMUX" ] && ([ "${TERM%%-*}" = "tmux" ] || [ "${TERM%%-*}" = "screen" ] ); then
# Tell tmux to pass the escape sequences through
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\\" "$1"
fi
}This works also for dash.
For fish put this in your ~/.config/fish/config.fish:
function vterm_printf;
if begin; [ -n "$TMUX" ] ; and string match -q -r "screen|tmux" "$TERM"; end
# tell tmux to pass the escape sequences through
printf "\ePtmux;\e\e]%s\007\e\\" "$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\\" "$argv"
end
endIf you have successfully built the module, you can test it by executing the
following command in the build directory:
make runOpen a terminal in the current window.
Open a terminal in another window.
When you enable vterm-copy-mode, the terminal buffer behaves like a normal
read-only text buffer: you can search, copy text, etc. The default keybinding
to toggle vterm-copy-mode is C-c C-t. When a region is selected, it is
possible to copy the text and leave vterm-copy-mode with the enter key.
If no region is selected when the enter key is pressed it will copy the current
line from start to end. If vterm-copy-exclude-prompt is true it will skip
the prompt and not include it in the copy.
vterm-clear-scrollback does exactly what the name suggests: it clears the
current buffer from the data that it is not currently visible.
vterm-clear-scrollback is bound to C-c C-l. This function is typically used
with the clear function provided by the shell to clear both screen and
scrollback. In order to achieve this behavior, you need to add a new shell alias.
For zsh, put this in your .zshrc:
if [[ "$INSIDE_EMACS" = 'vterm' ]]; then
alias clear='vterm_printf "51;Evterm-clear-scrollback";tput clear'
fiFor bash, put this in your .bashrc:
if [[ "$INSIDE_EMACS" = 'vterm' ]]; then
function clear(){
vterm_printf "51;Evterm-clear-scrollback";
tput clear;
}
fiFor fish:
if [ "$INSIDE_EMACS" = 'vterm' ]
function clear
vterm_printf "51;Evterm-clear-scrollback";
tput clear;
end
end
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 (i.e., calling C-u C-l).
Shell to run in a new vterm. It defaults to $SHELL.
to add more environment variables there is the custom vterm-environment which has a similar format than the internal Emacs variable process-environment. You can check the documentation with C-h v process-environment for more details.
Value for the TERM environment variable. It defaults to xterm-256color. If
eterm-256color is installed,
setting vterm-term-environment-variable to eterm-color improves the
rendering of colors in some systems.
If set to t, buffers are killed when the associated process is terminated (for
example, by logging out the shell). Keeping buffers around it is useful if you
need to copy or manipulate the content.
Compilation flags and arguments to be given to CMake when compiling the module.
This string is directly passed to CMake, so it uses the same syntax. At the
moment, it main use is for compiling vterm using the system libvterm instead of
the one downloaded from GitHub. You can find all the arguments and flags
available with cmake -LA in the build directory.
Controls whether or not to exclude the prompt when copying a line in
vterm-copy-mode. Using the universal prefix before calling
vterm-copy-mode-done will invert the value for that call, allowing you to
temporarily override the setting. When a prompt is not found, the whole line is
copied.
The variable vterm-use-vterm-prompt-detection-method determines whether to use
the vterm prompt tracking, if false it use the regexp in
vterm-copy-prompt-regexp to search for the prompt.
Vterm support copy text to Emacs kill ring and system clipboard by using OSC 52. See https://invisible-island.net/xterm/ctlseqs/ctlseqs.html for more info about OSC 52. For example: send 'blabla' to kill ring: printf "\033]52;c;$(printf "%s" "blabla" | base64)\a"
tmux can share its copy buffer to terminals by supporting osc52(like iterm2 xterm), you can enable this feature for tmux by : set -g set-clipboard on #osc 52 copy paste share with iterm set -ga terminal-overrides ',xterm*:XT:Ms=\E]52;%p1%s;%p2%s\007' set -ga terminal-overrides ',screen*:XT:Ms=\E]52;%p1%s;%p2%s\007'
The clipboard querying/clearing functionality offered by OSC 52 is not implemented here, And for security reason, this feature is disabled by default."
This feature need the new way of handling strings with a struct VTermStringFragment
in libvterm. You'd better compile emacs-libvterm with cmake -DUSE_SYSTEM_LIBVTERM=no ...
If you don't do that, when the content you want to copied is too long, it would be truncated
by bug of libvterm.
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;${HOSTNAME}:${PWD}\007"'For fish,
function fish_title
hostname
echo ":"
pwd
endSee zsh and bash and fish documentations.
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.
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.
You can change the font (the face) used in a vterm with the following code:
(add-hook 'vterm-mode-hook
(lambda ()
(set (make-local-variable 'buffer-face-mode-face) 'fixed-pitch)
(buffer-face-mode t)))Where instead of 'fixed-pitch you specify the face you want to use. The
example reported here can be used to force vterm to use a mono-spaced font (the
fixed-pitch face). This is useful when your default font in Emacs is a
proportional font.
In addition to that, you can disable some text properties (bold, underline,
reverse video) setting the relative option to t (vterm-disable-bold,
vterm-disable-underline, or vterm-disable-inverse-video).
When vterm-ignore-blink-cursor is t, vterm will ignore request from application to turn on or off cursor blink.
If nil, cursor in any window may begin to blink or not blink because blink-cursor-mode
is a global minor mode in Emacs, you can use M-x blink-cursor-mode to toggle.
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-black
- vterm-color-red
- vterm-color-green
- vterm-color-yellow
- vterm-color-blue
- vterm-color-magenta
- vterm-color-cyan
- vterm-color-white
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 --copy 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
endHere we are using the function vterm_printf that we have discussed above, so make
sure that this function is defined in your configuration file.
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)"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. A convenient shell function to
automate the substitution is
bash or zsh:
vterm_cmd() {
local vterm_elisp
vterm_elisp=""
while [ $# -gt 0 ]; do
vterm_elisp="$vterm_elisp""$(printf '"%s" ' "$(printf "%s" "$1" | sed -e 's|\\|\\\\|g' -e 's|"|\\"|g')")"
shift
done
vterm_printf "51;E$vterm_elisp"
}fish:
function vterm_cmd --description 'Run an Emacs command among the ones been defined in vterm-eval-cmds.'
set -l vterm_elisp ()
for arg in $argv
set -a vterm_elisp (printf '"%s" ' (string replace -a -r '([\\\\"])' '\\\\\\\\$1' $arg))
end
vterm_printf '51;E'(string join '' $vterm_elisp)
endNow we can write shell functions to call the ones defined in vterm-eval-cmds.
find_file() {
vterm_cmd find-file "$(realpath "${@:-.}")"
}
say() {
vterm_cmd message "%s" "$*"
}Or for fish:
function find_file
set -q argv[1]; or set argv[1] "."
vterm_cmd find-file (realpath "$argv")
end
function say
vterm_cmd message "%s" "$argv"
endThis newly defined find_file function can now be used inside vterm as
find_file name_of_file_in_local_directoryIf you call find_file without specifying any file (you just execute find_file in your shell),
dired will open with the current 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 ~/DocumentsThe configurations described in earlier sections are combined in
etc/. These can be appended to or loaded into your user
configuration file. Alternatively, they can be installed system-wide, for
example in /etc/bash/bashrc.d/, /etc/profile.d/ (for zsh), or
/etc/fish/conf.d/ for fish.
When using vterm Emacs sets the environment variable INSIDE_EMACS in the subshell to ‘vterm’. Usually the programs check this variable to determine whether they are running inside Emacs.
Vterm also sets an extra variable EMACS_VTERM_PATH to the place where the vterm library is installed. This is very useful because when vterm is installed from melpa the Shell-side configuration files are in the EMACS_VTERM_PATH inside the /etc sub-directory. After a package update, the directory name changes, so, a code like this in your bashrc could be enough to load always the latest version of the file from the right location without coping any file manually.
if [[ "$INSIDE_EMACS" = 'vterm' ]] \
&& [[ -n ${EMACS_VTERM_PATH} ]] \
&& [[ -f ${EMACS_VTERM_PATH}/etc/emacs-vterm-bash.sh ]]; then
source ${EMACS_VTERM_PATH}/etc/emacs-vterm-bash.sh
fi
By default, the scrollback can contain up to 1000 lines per each vterm buffer.
You can increase this up to 100000 by changing the variable
vterm-max-scrollback. If you want to increase it further, you have to edit the
file vterm-module.h, change the variable SB_MAX, and set the new value for
vterm-max-scrollback. The potential maximum memory consumption of vterm
buffers increases with vterm-max-scrollback, so setting SB_MAX to extreme
values may lead to system instabilities and crashes.
There is an option for that: set vterm-kill-buffer-on-exit to t.
The version of libvterm installed on your system is too old. You should let
emacs-libvterm download libvterm for you. You can either uninstall your
libvterm, or instruct Emacs to ignore the system libvterm. If you are compiling
from Emacs, you can do this by setting:
(setq vterm-module-cmake-args "-DUSE_SYSTEM_LIBVTERM=no")and compile again. If you are compiling with CMake, use the flag
-DUSE_SYSTEM_LIBVTERM=no.
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"))))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)We recommend that you set up shell-side configuration for reliable directory tracking. If you cannot do it, a possible workaround is the following.
On most GNU/Linux systems, you can read current directory from /proc:
(defun vterm-directory-sync ()
"Synchronize current working directory."
(interactive)
(when vterm--process
(let* ((pid (process-id vterm--process))
(dir (file-truename (format "/proc/%d/cwd/" pid))))
(setq default-directory dir))))A possible application of this function is in combination with find-file:
(advice-add #'find-file :before #'vterm-directory-sync)This method does not work on remote machines.
If you looked at the recommended way to set-up directory tracking, you will have
noticed that it requires printing obscure code like \e]2;%m:%2~\a (unless you
are using fish).
There is another way to achieve this behavior. Define a shell function, on a local host you can simply use
vterm_set_directory() {
vterm_cmd update-pwd "$PWD/"
}On a remote one, use instead
vterm_set_directory() {
vterm_cmd update-pwd "/-:""$USER""@""$HOSTNAME"":""$PWD/"
}Then, for zsh, add this function to the chpwd hook:
autoload -U add-zsh-hook
add-zsh-hook -Uz chpwd (){ vterm_set_directory }For bash, append it to the prompt:
PROMPT_COMMAND="$PROMPT_COMMAND;vterm_set_directory"Finally, add update-pwd to the list of commands that Emacs
is allowed to execute from vterm:
(add-to-list 'vterm-eval-cmds '("update-pwd" (lambda (path) (setq default-directory path))))When evil-mode is enabled, the cursor moves back in normal state, and this messes directory tracking
evil-collection provides a solution for this problem. If you do not want to
use evil-collection, you can add the following code:
(defun evil-collection-vterm-escape-stay ()
"Go back to normal state but don't move
cursor backwards. Moving cursor backwards is the default vim behavior but it is
not appropriate in some cases like terminals."
(setq-local evil-move-cursor-back nil))
(add-hook 'vterm-mode-hook #'evil-collection-vterm-escape-stay)- vterm-toggle: Toggles between a vterm and the current buffer
- multi-libvterm: Multiterm for emacs-libvterm
Obsolete variables will be removed in version 0.1.
vterm-disable-bold-fontwas renamed tovterm-disable-boldto uniform it with the other similar options.
vterm-use-vterm-promptwas renamed tovterm-use-vterm-prompt-detection-method.vterm-kill-buffer-on-exitis set totby default.
vterm-clear-scrollbackwas renamed tovterm-clear-scrollback-when-clearning.vterm-set-title-functionswas removed. In its place, there is a new custom optionvterm-buffer-name-string. See vterm-buffer-name-string for documentation.