Why capture command-line input and output?

为什么要捕获命令行输入和输出？

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If the output stream was stdout, and if it was piped to another process (at the command line level), the selected pages will become the input to that process.

如果输出流是标准输出，并且由管道输送至另一个进程(在命令行级别)，则选定的页将成为该进程的输入。

youdao

Once all the command line arguments are processed, the actual processing of the input starts, using the options and input and output sources and targets specified.

一旦处理了所有的命令行参数，就使用这些指定的选项以及输入、输出源和目标来开始输入的实际处理。

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