Another application which uses REs is the vi editor.
For purpose of an exercise we will create a file 'temp' in the current directory.
Open a file by typing:
vi temp
and enter the following two lines:
Tooting and froing
until tomorrow morning
Now suppose we want to search for a string starting with 't' and ending with 'ing'.
The correct regular expression is: t.*ing
Switch into the command mode by pressing
ESC
and type
/t.*ing 
ENTER
.
The cursor will point to the first character of the longest match 'ting and froing'.
Press
/ ENTER
and the cursor will move to the next match: 'til tomorrow morning'.
For more options refer to the UNIX in a nutshell book.