There's an old joke that Emacs would be a great operating system if only it had a decent text editor,
whereas vi would be a great text editor if only it had a decent operating system.

to remove blank lines please use following.

:g/^$/d

OR

:g/^ *$/d

To remove tailing space

:%s/\s\+$//

To remove space at beginning

:%s/^\s\+//

To replace tab with space you need to use

:%s/[CTRL-i]/ /g

To delete lines start with some word e.g. Redirect

:g/^Redirect/d

To remove Carriage return in vi use following

:%s/^M//g

NOTE : to create “^M” use “Ctrl+v Ctrl+M” Regular ^M does not help.

NOTE : This will apply to whole file as we are using (%)
To convert upper case use following

:%s/\([a-z]\)/\u\1/g

To convert lower case use following

:%s/\([A-Z]\)/\l\1/g

To Match Start of line and append that line use following
(search Append end of line)

%g/^DocumentRoot/s/$/\/www/

Which append “/www” if start of line is “DocumentRoot”.

Also you can append after word by following.

%s/word/&test/g

So all word is get replaced by “wordtest”.

Introduction to vim scripts “:help vim-script-intro”

There is many way to run vim script simple way is to run calling script from `source`

:source /home/yahoo/test.vim

You can also call command from script directly

:call MyBackupFunc(expand('%'), { 'all':1, 'save':'recent'})

You can do mapping of the keyboard using the variables.

:nmap ;s :source /home/yahoo/test.vim<CR>

The key sequence `;s` will execute the specified script file
You can call fucntion using the stored mapping same way.

:nmap \b :call MyBackupFunc(expand('%'), { 'all': 1 })<CR>

To call the function you need to call enter squence `\b`

VIM support syntax highlighting. to turn it on.

:syntax on

to turn it off

:syntax off

function! ToggleSyntax()
   if exists("g:syntax_on")
      syntax off
   else
      syntax enable
   endif
endfunction
 
nmap <silent>  ;s  :call ToggleSyntax()<CR>

`;s` sequence to flip syntax highlighting on or off every time typed when you're in Normal mode.
nmap stands for “normal-mode key mapping”.
<silent> option causes the mapping not to echo any command it's executing.

function! CapitalizeCenterAndMoveDown()
   s/\<./\u&/g   "Built-in substitution capitalizes each word
   center        "Built-in center command centers entire line
   +1            "Built-in relative motion (+1 line down)
endfunction
 
nmap <silent>  \C  :call CapitalizeCenterAndMoveDown()<CR>

single backslash used for continuation marker

call SetName(
\             first_name,
\             middle_initial,
\             family_name
\           )

Also you can use “|” to write two line on singe line.

echo "Starting..." | call Phase(1) | call Phase(2) | echo "Done"

You can comment using single quote, as double quote used to define a string.
also you can use “|” to escape the comment in some cases.

echo "> " |"Print generic prompt

to define variable you need to use word `let`

let name = "Damian"
let height = 165
let interests = [ 'Cinema', 'Literature', 'World Domination', 101 ]
let phone     = { 'cell':5551017346, 'home':5558038728, 'work':'?' }

• scalar: a single value, such as a string or a number. For example: “Damian” or 165
• list: an ordered sequence of values delimited by square brackets, with implicit integer indices starting at zero. For example: ['Cinema', 'Literature', 'World Domination', 101]
• dictionary: an unordered set of values delimited by braces, with explicit string keys. For example: {'cell':5551017346, 'home':5558038728, 'work':'?'}

g: varname  	 The variable is global
s: varname 	The variable is local to the current script file
w: varname 	The variable is local to the current editor window
t: varname 	The variable is local to the current editor tab
b: varname 	The variable is local to the current editor buffer
l: varname 	The variable is local to the current function
a: varname 	The variable is a parameter of the current function
v: varname 	The variable is one that Vim predefines

& varname  	 A Vim option (local option if defined, otherwise global)
&l: varname 	A local Vim option
&g: varname 	A global Vim option
@ varname 	A Vim register
$ varname 	An environment variable