How to setup a line length marker in vim/gvim?

Just execute this

:set colorcolumn=72

You can also prefix the argument with - or + to put the marker that many columns to the left or right of textwidth, and it accepts a comma-separated list of columns. I think the colorcolumn option is only in Vim 7.3. See

:help colorcolumn

From Damian Conway's "More Instantly Better Vim" talk at OSCON 2013:

highlight ColorColumn ctermbg=magenta
call matchadd('ColorColumn', '\%81v', 100)

This results in the character being highlighted in magenta (the screenshot is in DarkCyan) when the line goes over the 80-character maximum.

For gVim: it's best to move those 2 lines to the last part of your .vimrc file to ensure it works.

You could try this:

grep '.\{81\}' file

or

set colorcolumn=80

(or the shorthand equivalent)

set cc=80

or as aforementioned:

match ErrorMsg '\%>80v.\+'

Below is a clumsy trick from Hacking Vim: A Cookbook to get the Most out of the Latest Vim Editor by Kim Schultz.

It highlights with ErrorMsg (usually bright red) any lines that go over 80 characters. Works well for me.

function! RemoveWidthLimitWarnigns()
    silent! call matchdelete(4)
endfunction
function! InsertWidthLimitWarnings()
    call RemoveWidthLimitWarnigns()
    call matchadd("ErrorMsg", "\\%>79v.\\+", 10, 4)
endfunction