The command-line client

For the machines that have no clipboard at all. It reads standard input and writes standard output, so it composes with everything else you already use — and it is not a second implementation, it imports the very same encryption and transport files the browser runs.

Not on npm yet. npx realtimeclipboard is what it will be; until the first release is published, run the same client from a clone — node cli/realtimeclipboard.mjs D75LV. Every command below works either way.

Install it

npx realtimeclipboard D75LV

There is nothing to install: npx fetches it, runs it and leaves nothing behind. If you would rather have it on your path:

npm install -g realtimeclipboard

Node 22 or newer is required, for the built-in WebSocket. On an older Node the client exits immediately and says so rather than failing halfway through a transfer.

Or from a package manager

brew install akshaynikhare/tap/realtimeclipboard-cli

Note the name: the CLI formula is realtimeclipboard-cli and the desktop app is the realtimeclipboard cask. They are different things and installing one does not give you the other — a server wants the pipe, not a menu-bar icon.

Check it worked

npx realtimeclipboard --version

Connecting prints one status line to standard error, never standard output:

realtimeclipboard · room 3f2a91c4…

That is the room hash, truncated — never the key. Because it goes to stderr, watch > file still writes only the clip. Pass -q to silence it entirely.

Your first sync

Open the app in a browser and note the key.

On the server, send something to it:

echo "deploy key" | npx realtimeclipboard send D75LV

It appears in the browser. Now go the other way — copy something in the browser, and on the server run:
```
npx realtimeclipboard watch D75LV --once > token.txt
```

The four commands

Command	What it does
`realtimeclipboard <KEY>`	Two-way: prints what arrives, sends what you type
`realtimeclipboard watch <KEY>`	Print incoming clips
`realtimeclipboard send <KEY>`	Read stdin to EOF and send it
`realtimeclipboard new [--long]`	Print a fresh key

Options: --relay <url>, --pin <pin>, --once, --json, --timeout <s>, -q, -h, -v. The relay and the PIN also read from REALTIMECLIPBOARD_RELAY and REALTIMECLIPBOARD_PIN, which is the right way to pass a PIN — an argument lands in your shell history.

# structured output, one JSON object per line
npx realtimeclipboard watch D75LV --once --json | jq -r .text

# from a box you are ssh'd into
ssh build-01 'cat /var/log/deploy.log' | npx realtimeclipboard send D75LV

# against your own relay
npx realtimeclipboard --relay wss://clip.example.com D75LV

When it does not work

“this needs Node 22 or newer”

Exactly what it says: the client uses Node's built-in WebSocket rather than pulling a dependency in, and that landed in 22. It exits at startup rather than mid-transfer.

It hangs and never prints anything

watch waits for a clip by design — nothing arrives until something is copied at the other end. Use --timeout 30 in a script so it cannot wait forever, and --once so it exits after the first clip.

It works interactively but not in CI

There is no TTY, so pass -q and read standard output. Put the key in an environment variable rather than the command line, where it would show up in build logs.

Nothing connects from behind a proxy

The client speaks the same protocol as the browser and can be pointed at your own relay with --relay. Running one is one container.

Uninstalling

npx leaves nothing to uninstall. npm uninstall -g realtimeclipboard if you installed it globally, or brew uninstall realtimeclipboard-cli.

The key is a bearer credential. Anyone holding it can read the session while it is open, so keep it out of shell history, out of CI logs and out of committed files. Clip contents are encrypted on this machine before they are sent; the relay only ever sees a room hash and ciphertext.

Every other platform: the installation guide. Something wrong or out of date here? Open an issue.