klipsustreamer

A simple and lightweight CLI tool to monitor clipboard changes and output the contents as a JSON stream, intended to be called by external applications to monitor clipboard events.

As there is no way to listen to clipboard events it uses a polling method. But instead of reading the clipboard contents continuously, it will look for the changeCount number provided by NSPasteboard. It is a counter that increases every time the clipboard contents change. Therefore the implementation is lightweight and consumes minimal amounts of memory and CPU, even with fast polling times.

Installation

Option 1

Download the binary from https://github.com/lahdekorpi/klipsustreamer/releases and run the klipsustreamer executable.

Option 2

Download or clone the sources and open the project with Xcode, then build.

Option 3

Run:  

sudo wget https://github.com/lahdekorpi/klipsustreamer/releases/download/v1.0.1/klipsustreamer -O /usr/local/bin/klipsustreamer && sudo chmod a+rx /usr/local/bin/klipsustreamer

Make sure you have /usr/local/bin in your $PATH

Usage

klipsustreamer is a command line application intended to be called from another application that reads its JSON output, instead of having to implement a pbpaste or other implementation.
When you start klipsustreamer it will output to stdout a JSON object with the current clipboard contents and a new line (\n), as is every time the clipboard content changes (NSPasteboard changeCount).

The JSON contains the data in UTF-8 as data and the type of the data available from the pasteboard in type as a string, in prioritized order: html, rtf or text. Meaning, if HTML and RTF are available, HTML is outputted.

Options

As there is currently no known way of listening to clipboard events reliably, a polling method is used instead.
You can change the polling interval with -i <seconds>. It defaults to 0.1. By default it's enough to just bundle and call klipsustreamer and parse for every \n found.

Output examples:

Text:

{"type":"text","data":"Hello World!"}

HTML:

{"type":"html","data":"<meta charset='utf-8'><span style=\"color: rgb(0, 0, 0); font-family: &quot;helvetica neue&quot;; font-size: medium; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial; display: inline !important; float: none;\">Hello World!<\/span>"}

RTF:

{"type":"rtf","data":"{\\rtf1\\ansi\\ansicpg1252\\cocoartf1504\\cocoasubrtf830\n{\\fonttbl\\f0\\fswiss\\fcharset0 Helvetica;}\n{\\colortbl;\\red255\\green255\\blue255;}\n{\\*\\expandedcolortbl;;}\n\\pard\\tx566\\tx1133\\tx1700\\tx2267\\tx2834\\tx3401\\tx3968\\tx4535\\tx5102\\tx5669\\tx6236\\tx6803\\pardirnatural\\partightenfactor0\n\n\\f0\\b\\fs24 \\cf0 Hello World!}"}

FAQ

Why not listen to keyboard CMD+C?

This is a common way to enhance the polling method. It however must be noted that there are multiple ways to copy stuff to the clipboard (through context menus, functionality in applications, automation etc). Using CMD+C is just one of those.
Since klipsustream is so lightweight, it can be used with short polling times eliminating the need for external triggers.

Why not images or other data?

At this moment, the focus is on outputting JSON data that can easily be parsed. Outputting images or other data would require to either base64 encode the data or find an alternative data transfer method for this. Pull requests are welcome though.