prevent crash of soldier when binary is not found

Signed-off-by: Leo Chen <leo@harmony.one>

utils/utils.go

@@ -3,7 +3,10 @@ package utils
 import (
 	"bytes"
 	"encoding/binary"
+	"errors"
+	"fmt"
 	"log"
+	"os"
 	"os/exec"
 	"regexp"
 	"strconv"
@@ -34,6 +37,9 @@ func GetUniqueIdFromPeer(peer p2p.Peer) uint16 {
 
 // RunCmd Runs command `name` with arguments `args`
 func RunCmd(name string, args ...string) error {
+	if _, err := os.Stat(name); os.IsNotExist(err) {
+		return errors.New(fmt.Sprintf("file: %v doesn't exist", name))
+	}
 	cmd := exec.Command(name, args...)
 	if err := cmd.Start(); err != nil {
 		log.Fatal(err)