conchtest.clj

(ns conchtest.core
  (:require [me.raynes.conch.low-level :as sh] ;; https://github.com/Raynes/conch
            [clojure.java.io :as io])) ;; clojurified Java classes

(defn lines
  []
  ;; ->> is a 'threading operator' - it allows us to write
  ;; call pipelines in a more natural order.
  ;; See doc at: http://clojuredocs.org/clojure_core/clojure.core/-%3E%3E
  (->>
    ;; get an infinite sequence: [1 2 3 4 5] etc.
    (iterate inc 1)
    ;; take the 5000 first elements
    (take 5000)
    ;; multiply each element by 11
    (map (fn [x] (* x 11)))
    ;; put all those element on individual lines, in a single string
    (reduce (fn [k v] (str k "\n" v)))))

(defn -main
  []

  ;; cat is just the identity function
  (def cat (sh/proc "cat"))

  ;; grep filters lines that contains "112"
  (def grep (sh/proc "grep" "112"))

  ;; generate 5K lines and feed them to cat
  (io/copy (lines) (cat :in))
  (.close (cat :in))

  ;; pipe cat output to grep
  (io/copy (cat :out) (grep :in))
  (.close (grep :in))

  ;; display grep output
  (sh/stream-to-out grep :out))