The watcher module provides functions for 'watching' a file for modifications and processing any new bytes in Go.

To install the module, simply run:

$ go get github.com/walkert/watcher

The watcher module can be used in two modes: standard and channel.

Simply call New with the name of the file to be watched. You can then call WasModified which simply returns a boolean based on whether or not the file was modified or GetNewBytes which will return a byte slice containing any new bytes seen.

If you supply the WithChannelMonitor option to New, the watcher will operate in channel mode. At every interval specified, the watcher will get any new bytes using GetNewBytes and send them to the ByteChannel. Any errors will be sent to the ErrChannel.

The example below shows a simple watcher usage in channel mode

package main

import (
    "fmt"
    "log"

    "github.com/walkert/watcher"
)

func main() {
    w, err := watcher.New("/path/to/file", watcher.WithChannelMonitor(25))
    if err != nil {
        log.Fatal(err)
    }
    for {
         select {
         case bytes := <-w.ByteChannel:
             fmt.Printf("Received %d bytes from file\n", len(bytes))
         case err := <-w.ErrChannel:
             log.Fatalf("Received error from watcher: %v\n", err)
             return
         }
     }
}