У вашего броузера проблема в совместимости с HTML5
IN this video we know about basic tail ,head , mkdir, touch commend.
The head command reads the first few lines of any text given to it as an input and writes them to standard output (which, by default, is the display screen).Linux tail command syntax. Tail is a command which prints the last few number of lines (10 lines by default) of a certain file, then terminates.