Execute Piped Shell Commands in Go

bashpipe.go

package main

import (
        "bytes"
        "io"
        "log"
        "os"
        "os/exec"
)

func Execute(output_buffer *bytes.Buffer, stack ...*exec.Cmd) (err error) {
        var error_buffer bytes.Buffer
        pipe_stack := make([]*io.PipeWriter, len(stack)-1)
        i := 0
        for ; i < len(stack)-1; i++ {
                stdin_pipe, stdout_pipe := io.Pipe()
                stack[i].Stdout = stdout_pipe
                stack[i].Stderr = &error_buffer
                stack[i+1].Stdin = stdin_pipe
                pipe_stack[i] = stdout_pipe
        }
        stack[i].Stdout = output_buffer
        stack[i].Stderr = &error_buffer

        if err := call(stack, pipe_stack); err != nil {
                log.Fatalln(string(error_buffer.Bytes()), err)
        }
        return err
}

func call(stack []*exec.Cmd, pipes []*io.PipeWriter) (err error) {
        if stack[0].Process == nil {
                if err = stack[0].Start(); err != nil {
                        return err
                }
        }
        if len(stack) > 1 {
                if err = stack[1].Start(); err != nil {
                        return err
                }
                defer func() {
                        if err == nil {
                                pipes[0].Close()
                                err = call(stack[1:], pipes[1:])
                        } else {
                                stack[1].Wait()
                        }
                }()
        }
        return stack[0].Wait()
}

func main() {
        var b bytes.Buffer
        if err := Execute(&b,
                exec.Command("find","/Users/tyndyll/Downloads", "-name", "*pdf"),
                exec.Command("sort", "-r"),
        ); err != nil {
                log.Fatalln(err)
        }
        io.Copy(os.Stdout, &b)
}