无法在golang中使用“ ”正确分割字符串

Question

I am trying to split the output of free command into 3 lines. A general output of free is

total used free shared buff/cache available Mem: 16309236 11129884 860300 534300 4319052 4306208 Swap: 20971516 234236 20737280

But when I am using strings.Split() of golang the Split function is now behaving as expected. I tried debugging it but could not find anything.

Kindly help.

package main

import "os/exec"
import "github.com/golang/glog"
import "fmt"
import "strings"
import "errors"

func thisWorks() {
    str_out := "hello world 
 How are you 
this is good"
    lines := strings.Split(str_out, "
")
    fmt.Printf("lines is  
%s
", lines)
}

func GetFreeOutput() error {

    var errMsg string
    bytes_out, err := exec.Command("free").Output()

    // This shows that the output has 10 (newline) in it.
    fmt.Println(bytes_out)

    if err != nil {
        errMsg = "Error geting output of free command"
        glog.Fatal(errMsg)
        return errors.New(errMsg)
    }

    str_out := string(bytes_out)
    fmt.Printf("str_out is  
%s", str_out)

    // This is not splitting the lines, it is converting the whole output to a single line.
    fmt.Println("
Lines are ", strings.Split(str_out, "
"))

    index_of_newline := strings.Index(str_out, "
")

    // This gives the index of "
" as 79 on my machine, which is correct.
    fmt.Printf("
Index is %d", index_of_newline)

    fmt.Println("
Line using index are ", strings.Split(str_out, string(str_out[index_of_newline])))

    return nil
}

func main() {
    err := GetFreeOutput()
    fmt.Printf("Error is %s", err)
}

Answer 1

Split is working as you expect. The issue is with how you print the lines.

The second argument to Println below is a slice.

 // This is not splitting the lines, it is converting the whole output to a single line.
fmt.Println("
Lines are ", strings.Split(str_out, "
"))

Per the fmt documentation, a slice is printed as:

[elem0 elem1 ...]

Notice that elements are separated by spaces. Splitting by and printing will in effect replace with ' '. Try this code to confirm that split is working as expected:

for i, line := range strings.Split(str_out, "
") {
   fmt.Println(i, line)
}