1·If a filename arg was not given on the command line, we use stdin.
如果命令行上没有给出文件名参数,我们就使用标准输入。
2·Secondly, because sed is a stream editor, it can perform edits to data it receives from stdin, such as from a pipeline.
其次,因为sed是一种流编辑器,所以,它可以对从如管道这样的标准输入接收的数据进行编辑。
3·Is it possible to modify stdin for some daily commands?
它是可能的修改一些日常命令的标准输入?
4·How can I safely and simply read a line of text from a file or stdin?
我如何能安全简单地读取一行文本从文件或标准输入?