This is because, again, sed only reads from the file you specify on the command line, using it as input — it doesn't try to modify the file.

这还是因为sed只读取在命令行指定的文件，将其用作输入——它不试图修改该文件。

youdao

When the user is typing a command on the command line-that is, the shell he or she is using-the user only sees stdin, or standard in-that is, input that the user or a program provides.

当用户在命令行(即用户正在使用的shell)中键入命令时，用户只能看到stdin(即标准输入)，这是用户或程序提供的输入。

youdao

Programs that take only command-line arguments as input, and produce potentially complicated output, can be very useful.

仅接受命令行参数作为输入并潜在地产生复杂输出的程序可能非常有用。

youdao