You'll also notice that we've replaced the 'd' command with the 'p' command, which as you might guess, explicitly commands sed to print the pattern space.
您还会注意到，我们用' p '命令替换了' d '命令，如您所猜想的那样，这明确要求sed打印模式空间。
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The third thing to notice is the use of single quotes to surround the 'd' command.