Sample unix-style filter that reads from STDIN sans args.

filter.coffee

#!/usr/bin/env coffee
fs = require 'fs'

transform = (data) -> 
  result = data.toString().replace /h/g, 'm'
  process.stdout.write result

if process.argv.length > 2
  transform fs.readFileSync(file, 'utf8') for file in process.argv[2..]
else
  process.stdin.on 'data', transform
  process.stdin.resume()

usage.md

filter.coffee

A sample coffee [filter](http://en.wikipedia.org/wiki/Filter_(Unix\)).

$ echo "hi world" | filter.coffee
mi world

$ cat hello.txt
hello world! 

$ filter.coffee hello.text
mello world!