wy , dans le message

<12860744.552.1318108707588.JavaMail.geo-discussion-forums_at_prmr13>, a

 ?crit?:

> If I type a string that ends with '\n', it operates as excepted;

> If I type a newline(immediately after '\n') that consists and only

> consists of EOF, it exits as excepted;

> But if I type a string that ends with EOF, it operates as if I typed a

> '\n', and so it echoes, the only difference is that it doesn't change to a

> new line.

> So, why it operates differently when encounters a newline that consists

> and only consists of EOF and a newline that starts with a normal character

> and ends with EOF?

I believe you are confusing two meanings for the EOF acronym.

There is an EOF constant in standard C, which is the special code that the

stdio input functions return when they encounter what they believe is the

end of file or a read error. This is usually -1, and in particular is not

equal to any character.

There is an EOF key associated to the terminal. When the terminal is in

"cooked mode", keys that are typed are not transmitted to the process

reading from it immediately. Instead, they are fed to a rudimentary line

editing system that allows to correct with backspace, etc. The LF character

causes the current contents of the line editing buffer to be sent to the

reading process, including the LF character itself. The EOF key does the

same thing, except it is not added to the buffer.

So if you type "hello<LF>", the process reads "hello\n", while if you type

"hello<EOF>", the process reads "hello".

The EOF key is called like that because if you type it when the line editing

buffer is empty, the reading process will read 0 bytes, and that is usually

interpreted as the end of the stream.

> It must have something to do with "line buffered", but I cannot understand.

"Line buffered" usually refers to the output buffer of a stdio stream, not

input. That has nothing to do with your problem.

> After invoking popen(), is the terminal associated with both stdins,

> stdouts, and stderrs of the parent process and the child process?

Well, obviously not, that is the whole point of popen: to have either the

standard input or standard output of the process you start connected to a

pipe, itself connected to a stream to the running process. The other one is

unchanged, as is stderr.