Fun with Named Pipes

Fun with named pipes

Shell 1 // this will create a named pipe @ /tmp/gfifo and read from the pipe 4eva
> ./gopipe
2014/03/12 20:53:35 Created Pipe

Shell 2
> echo "ASD" > /tmp/gfifo

Shell 1 // prints bytes
> [65 83 68]

gopipe.go

package main

import (
  "bufio"
  "fmt"
  "os"
  "os/exec"
  "os/signal"
  "log"
)

func main() {
    createPipe()
    defer cleanUpPipe()
    initSigs()
    read()
}

// create a named pipe on start up using mknod
func createPipe() {
    _ , err := exec.Command("mknod", "/tmp/gfifo", "p").Output()
    if err != nil{
        panic(err)
    }

    log.Print("Created Pipe")

}

// clean up the named pipe
func cleanUpPipe() {
    err := os.Remove("/tmp/gfifo")
    if err != nil{
        panic(err)
    }
    log.Print("Cleaned Up Pipe")
}


func read() {
    f, err := os.Open("/tmp/gfifo")
    if err != nil{
        panic(err)
    }
    defer f.Close()

	scanner := bufio.NewScanner(f)
	for scanner.Scan() {
		fmt.Println(scanner.Bytes()) // Println will add back the final '\n'
	}

    if err := scanner.Err(); err != nil {
		fmt.Fprintln(os.Stderr, "reading input:", err)
	}

    read()
}

// capture os signals
func initSigs() { 
    c := make(chan os.Signal, 1)
	signal.Notify(c, os.Interrupt, os.Kill)

    go func() {
	s := <-c
	log.Print("Got signal: ", s)
        cleanUpPipe()
        os.Exit(1)
    }()

}