resolve go-python#169 (comment)

Author: glaukiol1

os/os.module.go

@@ -9,13 +9,13 @@ package os
 import (
 	"os"
 	"os/exec"
+	"runtime"
 	"strings"
 
 	"github.com/go-python/gpython/py"
 )
 
 func init() {
-
 	methods := []*py.Method{
 		py.MustNewMethod("getcwd", getCwd, 0, "Get the current working directory"),
 		py.MustNewMethod("getcwdb", getCwdb, 0, "Get the current working directory in a byte slice"),
@@ -172,18 +172,22 @@ func _exit(self py.Object, args py.Tuple) (py.Object, error) { // can never retu
 
 // os.system(command string) this function runs a shell command and directs the output to standard output.
 func system(self py.Object, args py.Tuple) (py.Object, error) {
-	if len(args) == 0 && !(objectIsString(args[0])) {
+	if len(args) != 1 {
 		return nil, py.ExceptionNewf(py.TypeError, "missing one required argument: 'command:str'")
 	}
 	var cargs []string
-	_carg, err := py.ReprAsString(args[0])
-	if err != nil {
-		return nil, py.ExceptionNewf(py.TypeError, "Unable to parse string") // this will never execute
+	_carg, ok := args[0].(py.String)
+	if !ok {
+		return nil, py.ExceptionNewf(py.TypeError, "str expected (pos 1), not"+args[0].Type().Name)
 	}
-	carg := strings.ReplaceAll(_carg, "'", "") // required
+	carg := strings.ReplaceAll(string(_carg), "'", "")
 
-	cargs = strings.Split(carg, " ")
-	command := exec.Command(cargs[0], cargs[1:]...)
+	var command *exec.Cmd
+	if runtime.GOOS != "windows" {
+		command = exec.Command("/bin/sh", "-c", carg)
+	} else {
+		command = exec.Command(cargs[0], cargs[1:]...)
+	}
 	outb, err := command.CombinedOutput() // - commbinedoutput to get both stderr and stdout -
 	if err != nil {
 		return nil, py.ExceptionNewf(py.OSError, err.Error())