开头的美元符号是Shell提示符。

The leading dollar sign is the shell prompt.

youdao

您可能已经看到，XQuery 中通过在标识符前加上美元符号（$）来定义变量。

You've already seen in XQuery that a variable is defined by putting a dollar sign ($) in front of an identifier name.

youdao

$somevar 可以对美元符号进行转义，避免在设置提示符的命令中对该变量进行解释，而是在显示提示符时对其进行解释。

The phrase \$somevar escapes the dollar sign, avoiding interpretation of the variable in the command where the prompt is set. Instead, the interpretation occurs whenever the prompt is drawn.

youdao