clippy: making clipboard work over SSH

Clippy is a tool to interact with your desktop environment from a remote SSH sessions: share clipboard contents, open URLs and show notifications on your desktop. This way, your remote neovim session can paste directly from your clipboard, and yanking in a remote session will end up in your local clipboard manager (e.g. clipmenud). Clippy uses the SSH connection (specifically UNIX domain socket forwarding), so the clipboard contents is encrypted during transmission.

This is an alternative to lemonade. However, the security on shared servers is improved as only the current user can share the link to the desktop.

Integrates with:

Linux/FreeBSD (for X11 needs package xsel, for Wayland needs package wl-clipboard);
Termux on Android;
Windows if run under WSL;
macOS.

Installation

For FreeBSD, Debian, Ubuntu, and Raspbian, add the bitpowder repository. See the instructions on that repository page.

For macOS:

brew tap bvgastel/clippy https://github.com/bvgastel/clippy
brew install --HEAD bvgastel/clippy/clippy

Update with brew reinstall bvgastel/clippy/clippy.

To build the project from the source, you need cmake and a C++ compiler:

cmake .
cmake --build .
cmake --install .

On Termux (Android) use:

cmake -DCMAKE_INSTALL_PREFIX=$PREFIX .
cmake --build .
cmake --install .

Usage

Clippy should be installed on both the client and the server. Use clippy ssh instead of ssh to connect to remote computers. Clippy set some additional options automatically for ssh.
If no clippy daemon is running, it automatically starts a clippy daemon that listens on a UNIX domain socket named /tmp/clipboard.username.something, which is forwarded through SSH.

Commands:

clippy ssh to set up a clippy ssh connection to a different host;
clippy get to retrieve the clipboard contents;
echo contents | clippy set to set the clipboard;
clippy notification [summary] [body] to show a notification.
clippy openurl [url] to open an URL in your default browser.
clippy command [command] [args] to execute a command on the desktop, such as a dmenu session. It forwards stdin, stdout, stderr, and copies over the exit code. Terminal sizes etc are not copied over.

If you execute these commands locally, they also work. Making them suitable for integration in generic config files used both for a server and a client.

Set up for specific programs

Some software needs custom config options. Setup depends on the software you are using:

sshd (on some platforms set automatically)

On modern Debian (>= bullseye), Ubuntu (>= focal), and Raspbian (>= bullseye), these settings are automatically included when you install clippy.

Your sshd_config on the server should have:

StreamLocalBindUnlink yes
AcceptEnv LC_CLIPPY

On Linux add Include /etc/ssh/sshd_config.d/* to your /etc/ssh/sshd_config.
On FreeBSD add Include /usr/local/etc/ssh/sshd_config.d/* to your /etc/ssh/sshd_config.

tmux

Use with tmux-yank (in ~/.tmux.conf):

# move x clipboard into tmux paste buffer
bind ] run "tmux set-buffer \"$(clippy get)\"; tmux paste-buffer"
set -g @override_copy_command 'clippy set'
set-option -g -a update-environment "LC_CLIPPY"
set-option -g -a update-environment "WAYLAND_DISPLAY"

The basic version, without any plugins (in ~/.tmux.conf):

bind ] run "tmux set-buffer \"$(clippy get)\"; tmux paste-buffer"
# move tmux copy buffer into x clipboard
bind -T copy-mode-vi y run "tmux save-buffer - | clippy set"
bind -T copy-mode-emacs y run "tmux save-buffer - | clippy set"
set-option -g -a update-environment "LC_CLIPPY"
set-option -g -a update-environment "WAYLAND_DISPLAY"

neovim

In .config/nvim/init.vim:

set clipboard+=unnamed,unnamedplus
let g:clipboard = {
      \   'name': 'ClippyRemoteClipboard',
      \   'copy': {
      \      '+': 'clippy set',
      \      '*': 'clippy set',
      \    },
      \   'paste': {
      \      '+': 'clippy get'
      \      '*': 'clippy get',
      \   },
      \   'cache_enabled': 0,
      \ }

For more custom neovim clipboard settings, see :help g:clipboard.

Supported commands

read clipboard
set clipboard
show message on desktop (with notify-send, on WSL use powershell.exe, on macOS use osascript)
open URL in browser on desktop
remote command, such as a remote dmenu session
view file on desktop
copy file to/from desktop
support rendering part of a i3statusbar on desktop: CPU usage, memory usage, custom things, work queue like nq status (with remote queue)

To Do

improve error handling: errors in the clippy daemon (such as xsel/wl-paste not found) should be propagated to clippy clients (so they can exit with a non zero exit code)
[ ]

Alternatives

http://sshmenu.sourceforge.net/articles/bcvi/

bvgastel/clippy