Show a vertical column markers in vim (very usefull to check identation)

To show a background line in the whole column 9 and 17

:set colorcolumn=9,17

or short

:set cc=9,17

To change the color to blue

:highlight ColorColumn ctermbg=blue

show line in the cursor column

exe 'set cc='.col('.')
Source: https://superuser.com/questions/249779/how-to-setup-a-line-length-marker-in-vim-gvim