Golang golang-exec (snippet)

Go programming example 'golang-exec'

golang-exec

Golang beginners example: golang-exec

package main

import (
    "fmt"
    "os/exec"
    "strings"
)

func pipe_cmd(cmds ...*exec.Cmd) ([]byte, error) {
    for i, cmd := range cmds[:len(cmds)-1] {
        out, err := cmd.StdoutPipe()
        if err != nil {
            return nil, err
        }
        cmd.Start()
        cmds[i+1].Stdin = out
    }

    ret, err := cmds[len(cmds)-1].Output()
    if err != nil {
        return nil, err
    }

    return ret, nil
}

func main() {
    datestr, err := exec.Command("date").Output()
    if err != nil {
        fmt.Println(err)
    }
    fmt.Print("Date String: ", string(datestr))

    var datecmd *exec.Cmd
    var lscmd *exec.Cmd

    //of course the following lines are realy useless (they are only for example purposes)
    datecmd = exec.Command("date", "+%d.%m.%Y %H:%M:%S")
    grep1 := exec.Command("grep", "-o", "\\d\\d.\\d\\d.\\d\\d\\d\\d")
    date, err1 := pipe_cmd(datecmd, grep1)

    datecmd = exec.Command("date", "+%d.%m.%Y %H:%M:%S")
    grep2 := exec.Command("grep", "-o", "\\d\\d:\\d\\d:\\d\\d")
    time, err2 := pipe_cmd(datecmd, grep2)

    lscmd = exec.Command("ls", "-ltraR", "./")
    grep3 := exec.Command("grep", "-o", "[^ \\./]\\+\\.[^ \\./]\\+")
    files, err3 := pipe_cmd(lscmd, grep3)

    if err1 != nil {
        fmt.Print(err1)
    } else {
        fmt.Print("Date: ", string(date))
    }

    if err2 != nil {
        fmt.Print(err2)
    } else {
        fmt.Print("Time: ", string(time))
    }

    counter := make(map[string]int)
    var ok bool
    if err3 != nil {
        fmt.Print(err3)
    } else {
        strarray := strings.Split(string(files), "\n")
        for i := 0; i < len(strarray); i++ {
            if strings.Trim(strarray[i], " .") != "" {
                if _, ok = counter[strarray[i]]; ok {
                    counter[strarray[i]]++
                } else {
                    counter[strarray[i]] = 1
                }
            }
        }
        fmt.Println("Files: ", counter)
    }
}

Useful links

• Learn Go: https://golangr.com
• Download Go: https://golang.org