在MacOS X Mavericks上重置root密码或启用sudo

我有一个MacOS X Mavericks安装，其中有一个用户Admin和该帐户的空密码：

现在，我正在尝试安装Cocoapods，但是不能使用“ sudo”，因为我不知道root密码：

admin@mac:etc> id
uid=501(admin) gid=20(staff) groups=20(staff),401(com.apple.sharepoint.group.1),12(everyone),61(localaccounts),79(_appserverusr),80(admin),81(_appserveradm),98(_lpadmin),33(_appstore),100(_lpoperator),204(_developer),398(com.apple.access_screensharing),399(com.apple.access_ssh)
admin@mac:etc> id root
uid=0(root) gid=0(wheel) groups=0(wheel),1(daemon),2(kmem),3(sys),4(tty),5(operator),8(procview),9(procmod),12(everyone),20(staff),29(certusers),61(localaccounts),80(admin),401(com.apple.sharepoint.group.1),33(_appstore),98(_lpadmin),100(_lpoperator),204(_developer),398(com.apple.access_screensharing),399(com.apple.access_ssh)
admin@mac:etc> sudo gem install cocoapods

WARNING: Improper use of the sudo command could lead to data loss
or the deletion of important system files. Please double-check your
typing when using sudo. Type "man sudo" for more information.

To proceed, enter your password, or type Ctrl-C to abort.

Password:
Sorry, try again.
Password:
Sorry, try again.
Password:
Sorry, try again.
sudo: 3 incorrect password attempts

在Linux上，我将以单用户模式启动计算机并设置root密码。或将Admin用户添加到滚轮分组中，并在/ etc / sudoers中取消注释此行：

%wheel  ALL=(ALL)       NOPASSWD: ALL

但是在MacOS中，我不知道该怎么办。

当我运行文本编辑器或MacVim时，我也找不到/ etc / sudoers。