Hi there I have a very stupid question I know that for different command there are different flags but for eg,
in here what is 's' and where I can find information about the things like this I just even does not how they are called to google and the same refer to
and how to make this thing by myself???:/
The s is a substitute command. It will match the pattern between the first and second slant characters, and replace it with what is between the second and third slant characters. That is very simplified. Have a look at the sed man page for starters.