STDOUT 通常是控制台，除非用户进行了重定向。

The STDOUT, unless redirected by the user, is usually the console.

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当cat的输出没有被重定向到一个文件或另一个命令的标准输出时，cat表现出来的行为与多数命令行工具一样，即将其输出发送到控制台。

When the output of cat is not redirected to a file or another command's standard input, cat behaves as most command-line tools and send its output to the console.

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