A real-time zero-configuration web-based tail

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A real-time zero-configuration web-based tail. It broadcasts events such as new lines added to any monitored files, new UDP messages, and those emitted by other EventEmitters to your browser.

The lucidtail Command

The lucidtail command listens to specified sources and displays them in a pretty little web application (see demo).

To quickly be able to view your logs at http://localhost:8080:

lucidtail *.log


After having nodejs installed:

Method: Simple

To install lucidtail globally:

npm install lucidtail -g

This allows you to use the lucidtail command. You may need root/Administrator access, if you don't have it you can alternately get lucidtail from the git repository.

Method: From GIT

Clone lucidtail:

git clone git://

You should now be able to use ./index.js or node index.js within the cloned directory instead of lucidtail.


lucidtail will use it's default http port (8080) when running.

For more information: lucidtail --help


Monitor all files ending with '.log':

lucidtail *.log

Monitor UDP messages on syslog port 514 (which requires root access on most systems):

lucidtail -u 514


On port 8081:

lucidtail *.log -u 514 -p 8081

lucidtail npm package

Install lucidtail as a dependency in your package.json:

cd example
npm init
npm install lucidtail --save

Monitor a test emitter (which sends a test message every second) and publish events on the default port (port 8080):


Monitors UDP messages on port 5000:

    .use('udp4', 5000);


The following will display inbound syslog messages (UDP port 514) on HTTP port 80:


  • This example uses lazy which is on npm.
  • Port 80 and 514 may require root/Administrator privileges to bind to.


var lucidtail = require('lucidtail'),
    lazy = require('lazy');

// Use a simple regex to parse out the values in the message
// Not even RFC 3164, but this is just an example.
var regex = /(<\d+>)?(\w{3} +\d+ \d{2}:\d{2}:\d{2})?( \w+)?( \w+\[?\d*\]?)?: (.*)/;
var syslog = lazy(lucidtail.emitter('udp4', 514))
    .map(function(data) {
        var matches =;
        if (matches) {
            if (matches[1])
                data.pri = matches[1].replace(/[<>]/g, '');
            if (matches[2])
       = matches[2];
            if (matches[3])
       = matches[3].substring(1);
            if (matches[4])
                data.application = matches[4].substring(1);
            if (matches[5])
                data.msg = matches[5];
        return data;

// Create aggregate emitter
var emitter = lucidtail(80)
    // Listen to a test emitter