Editors handy commands

Insert TEXT at beginning of a line
Notepad++
Search mode – regular expression
Find:   
^(.)
Replace with:   
TEXT\1

Vi
:%s/^/TEXT/

Append TEXT to end of a line
Notepad++
Search mode – regular expression
Find:
(.)$
Replace with:   
\1TEXT

Vi
:%s/$/TEXT/

Delete blank lines
Notepad++
Menu: TextFX -> TextFX Edit -> Delete blank lines

vi
:g/^$/d
Blank line with spaces (there is a space after backslash):
:g/^\ *$/d

Find “db.world” and replace with “db, db.world”
Notepad++
Search mode – regular expression
Find:   
^(\w*).world
Replace with:   
\1, \1.world