如何解决从Ant调用Ruby时不允许将`$('作为全局变量名'

我在努力适应 instructions from the Homebrew website 并运行与此等效的:

/usr/bin/ruby -e "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install)"

…从一个Ant构建文件。这里是:

<project name="default" default="homebrew">
    <target name="ruby" >
        <echo message="Checking Ruby..." />
        <exec executable="/usr/bin/ruby">
            <arg value="--version"/>
        </exec>
        <echo message="Checking Ruby done!" />
    </target>
    <target name="homebrew" depends="ruby">
        <echo message="Installing Homebrew..." />
        <exec executable="/usr/bin/ruby">
            <arg line=' -e "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install)"'/>
        </exec>
        <echo message="Homebrew installation done!" />
    </target>
</project>

我得到的是:

ruby:
     [echo] Checking Ruby...
     [exec] ruby 2.3.7p456 (2018-03-28 revision 63024) [universal.x86_64-darwin16]
     [echo] Checking Ruby done!

homebrew:
     [echo] Installing Homebrew...
     [exec] -e:1: `$(' is not allowed as a global variable name
     [exec] Result: 1
     [echo] Homebrew installation done!

我怎么才能避开这个 $(' is not allowed as a global variable name 有问题吗?有可能以某种方式逃离 $ 签字? 简而言之,我如何调整这个Ant构建文件来安装自制程序?我可以将Homebrew安装命令放在bash脚本中,但我更愿意直接从Ant修复语法。