public function execute()
    {
        $success = true;
        foreach ($this->env_vars as $key => $value) {
            if (is_numeric($key)) {
                // This allows the developer to specify env vars like " - FOO=bar" or " - FOO: bar"
                $env_var = is_array($value)? key($value).'='.current($value): $value;
            } else {
                // This allows the standard syntax: "FOO: bar"
                $env_var = "$key=$value";
            }

            if (!putenv($this->phpci->interpolate($env_var))) {
                $success = false;
                $this->phpci->logFailure(Lang::get('unable_to_set_env'));
            }
        }
        return $success;
    }