We can use another form of variable expansion to select a specific substring, based on a specific character offset and length. Try typing in the following lines under bash.

可以根据特定字符偏移和长度，使用另一种形式的变量扩展，来选择特定子字符串。

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For example, the "! "character is the history expansion character, which bash normally replaces with a previously-typed command.

例如，“ ！ ”字符是历史扩展字符，bash通常将其替换为前面输入的命令。

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You will notice that on a US keyboard, shift-4 is "$", which is the bash variable expansion character.

注意到了吗：在美国键盘上，shift-4 是 "$"，它是 bash 变量扩展字符。

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Harmondsworth Village in west London was designated a conservation area in 1970 but the open countryside famed for being a medieval settlement could lose its character because of the expansion of Heathrow Airport, according to English Heritage.

BBC: London's unique areas 'at risk'

An expansion pack is sorely needed at this point, however, and preferably one with a couple new playable character types and a bunch of new areas.

FORBES: Connect