1
00:00:04,290 --> 00:00:11,250
Before we have talked about processes and now you know how to use such utilities as top and top.

2
00:00:11,250 --> 00:00:17,940
And you know that when you enter any command along with possible options and arguments, separate process

3
00:00:17,940 --> 00:00:27,030
is created and there are short running processes like mkdir or long running processes like Bash or FF.

4
00:00:27,600 --> 00:00:34,230
Now it's finally time to explain you what are data streams of every process.

5
00:00:34,560 --> 00:00:43,410
And actually when process is running there are three different data streams called stdin stdout and

6
00:00:43,500 --> 00:00:44,430
stderr.

7
00:00:44,460 --> 00:00:46,290
Those are short names.

8
00:00:46,320 --> 00:00:54,660
Long names are standard in standard out and standard error standard in is inbound data stream.

9
00:00:54,660 --> 00:00:56,820
It comes into the process.

10
00:00:56,850 --> 00:01:05,319
Standard out and standard error are outbound data streams and please note that stdout and stderr are

11
00:01:05,319 --> 00:01:08,110
two different separated data streams.

12
00:01:09,070 --> 00:01:10,450
What it tells us.

13
00:01:10,480 --> 00:01:17,110
It tells us that you are able to redirect different streams to different other processes.

14
00:01:17,290 --> 00:01:20,980
And let me show you how by default, it actually behaves.

15
00:01:21,010 --> 00:01:25,360
Let me go to terminal and here type LS command.

16
00:01:25,360 --> 00:01:33,400
And please note that LHS starts LHS process and here we don't use any arguments and don't use any options.

17
00:01:33,430 --> 00:01:35,890
Simply LHS press enter.

18
00:01:35,890 --> 00:01:37,810
And here I see result.

19
00:01:38,140 --> 00:01:44,320
And this result was produced by stdout data stream.

20
00:01:45,230 --> 00:01:51,710
This text was produced by process and streamed via stdout data stream.

21
00:01:52,130 --> 00:01:56,570
Let me now enter mkdir command and press enter.

22
00:01:56,570 --> 00:01:59,060
And now I see actually error.

23
00:01:59,090 --> 00:02:05,360
This error was streamed via std error from mkdir process.

24
00:02:05,810 --> 00:02:13,700
But how we actually understand that here is error and here is data stream from stdout.

25
00:02:13,730 --> 00:02:15,680
Let me show you it in the next lecture.

26
00:02:15,710 --> 00:02:20,390
Now you need to keep in mind that there are three different data streams in every process.

27
00:02:20,570 --> 00:02:23,600
stdIn stdout and stderr error.

28
00:02:23,780 --> 00:02:25,220
I'll see you in the next lecture.