Fix runcmd substitution for install script

main.go

@@ -11,10 +11,11 @@ import (
 	"os"
 	"os/exec"
 	"os/user"
+	"path/filepath"
 	"strconv"
 	"strings"
 	"unicode"
-	"path/filepath"
+
 	"gopkg.in/yaml.v3"
 )
 
@@ -225,8 +226,7 @@ func processUserData(configDriveDir string) error {
 
 	// Run commands
 	for _, cmd := range cc.RunCmd {
-		cmdArgs := strings.Fields(cmd)
-		cmdArgs[0] = strings.Replace(cmdArgs[0], "/usr/local/custom_script", "/opt/custom_script", -1)
+		cmdArgs := strings.Fields(strings.Replace(cmd, "/usr/local/custom_script", "/opt/custom_script", -1))
 		output, err := exec.Command(cmdArgs[0], cmdArgs[1:]...).CombinedOutput()
 		if err != nil {
 			log.Printf("Error running command '%s': %s\n%s", cmd, err, output)