Viewing long output and scrolling up/down in tty terminals

To view long output from utilities like ls, 
you need to pipe the output into a pager, such as  
more or less : `ls | less`

The `|` (pipe) sends(, or pipes), the output from the command on the left (ls) into the input of the command on the right (less) as arguments. 

• Press the spacebar or `f`  to scroll down the output by a page. Or `d` for half-a-page.
• Press `b` or `ESC-v` to scroll up the output by a page. Or `u` for half-a-page
• Press the `q` key to quit the pager. 
• To search for some text type `/something`
• Try `man less` for more information.

 To scroll up/down in a terminal without support for mouse, just press `SHIFT + pgUP/pgDOWN`. Although the amount you can scroll depends on terminal's scrollback buffer.

Now, to increase scrollback buffer size-

• Press Ctrl-a then : and then type scrollback 10000
• to get a 10000 line buffer, for example.
• You can also set the default number of scrollback lines by adding defscrollback 10000
• to your ~/.screenrc file.
• Another tip: Ctrl-a i shows your current buffer setting.