static int is_known_shell(const char *shell_name)
{
	char *s, ret = 0;

	if (!shell_name)
		return 0;

	setusershell();
	while ((s = getusershell())) {
		if (strcmp(shell_name, s) == 0) {
			ret = 1;
			break;
		}
	}
	endusershell();
	return ret;
}
static int is_known_shell(const char *shell_name)
{
	char *s, ret = 0;

	if (!shell_name)
		return 0;

	setusershell();
	while ((s = getusershell())) {
		if (strcmp(shell_name, s) == 0) {
			ret = 1;
			break;
		}
	}
	endusershell();
	return ret;
}