Getting started with ex

The : (colon) is ex prompt where you can type ex text editor command or regular expression. Its time to open our demofile, use ex as follows:
$ ex demofile
"demofile" [noeol] 20L, 387C
Entering Ex mode. Type "visual" to go to Normal mode.
:

As you can see, you will get : prompt, here you can type ex command, type q and press ENTER key to exit from ex as shown follows: (remember commands are case sensetive)
: q
vivek@ls vivek]$

After typing the q command you are exit to shell prompt.