Press SHIFT + ZZ which is equivalent to :x which is equivalent to :wq, except that it only saves if the file has been changed.

:set tabstop=4
:retab

To toggle this in VI on the fly to switch off auto-indent

:set paste

and to switch it back on

:set nopaste

In .vimrc this can be set:

set copyindent

Another alternative via .vimrc is:

set clipboard=unnamed

That makes the default paste buffer map to X's clipboard.
When a bit of text is highlighted in a terminal, it can be pasted into vim by simply press p to paste. Similarly, one can yank things in vim (e.g. YY to yank the current line into the buffer) and middle click in any window to paste it.

in ~/.vimrc

filetype plugin indent on
" show existing tab with 4 spaces width
set tabstop=4
" when indenting with '>', use 4 spaces width
set shiftwidth=4
" On pressing tab, insert 4 spaces
set expandtab

1. Press v to select lines or test with cursor keys
2. Then press y to copy the selection or press d to cut the selection
3. Then press '> to skip to the end of the selection
4. Then press p to paste under the cursor or SHIFT+p to paste after the cursor

1. Copy the entire line by pressing yy (more info :help yy ) or cut using dd.
2. Paste the line by pressing p.