always-tail2

Node.js module for continuously tailing a file.

It differs from the always-tail module in that it tails from the end of a file rather than the beginning of the file by default. It also includes bugfixes and updates as the always-tail module appears to be no longer maintained.

It differs from other tail modules in that it survives truncates, file rollovers (e.g. mv /var/log/test /var/log/test.1), and unlink.

It does this by monitoring the filename, and when the inode changes, it will continue to read to the end of the existing file descriptor, then automatically read from the newly created file with the same name.

It emits a 'line' event when a new line is read.

Installation

npm install always-tail2

Example

var Tail = require('always-tail2');
var fs = require('fs');
var filename = "/tmp/testlog";

if (!fs.existsSync(filename)) fs.writeFileSync(filename, "");

var tail = new Tail(filename, '\n');

tail.on('line', function(data) {
  console.log("got line:", data);
});


tail.on('error', function(data) {
  console.log("error:", data);
});

tail.watch();

// to unwatch and close all file descriptors, tail.unwatch();

Usage

var Tail = require('always-tail2');
var tail = new Tail(filename, separator, options);

filename - filename to monitor
separator - (default: \n) optional separator for each line
options.interval - (default: 1000) optional interval, in milliseconds, to check for changes
options.start - optional start byte to start reading from
options.startAtEnd - (default: true) set to true to start from end of file or false to start from beginning of file; ignored if options.start is set

Credits

Code is forked from the node-tail module (https://github.com/jandre/always-tail)

License