VIM textwidth has no effect

Try gggqGto apply the new text width to the whole buffer.

• gg means : go to the beginning of buffer
• gq means : reformat the text included in the motion
• G means : go to the end of the buffer

(It will works if the format options are correctly set, as detailed in Zyx post)

On the other hand, you could also display your existing text with a width of 72 characters by adding a modeline at the beginning or end of your file. See :help modeline

Something like vim:tw=72 should work.

I was looking for an answer to the same question and had to scramble around a bit before I found the solution in the VIM docs. So, i thought i will update the thread and save others the time.

The problem in my case was that the default ftplugin was disabling textwidth.

Just updating your .vimrc with (:set tw=79 && :set formatoptions+=t) won't work since the fplugins are sourced after vimrc.

Here are the steps that i followed:

1) find out what your current formatoptions (inside vim)

:set formatoptions?formatoptions=croql (note no 't')

2) create a filetype.vim file as suggested by vimdocs (http://vimdoc.sourceforge.net/htmldoc/filetype.html#ftplugin-overrule)

Overrule the settings after loading the global plugin.You must create a new filetype plugin in a directory from the end of'runtimepath'.  For Unix, for example, you could use this file:    vim ~/.vim/after/ftplugin/fortran.vimIn this file you can change just those settings that you want to change.

3) add the line :set formatoptions+=t && :set textwidth=79 in that file.

Voila! next time when you open the file it will set the textwidth to your desired characters.

As a debugging aid you can always check which file is overriding your vimrc setting by prepending your command with verbose. So for e.g. if i want to check who updated the formatoptions last, i would type

:verbose set formatoptions? formatoptions=croqltLast set from ~/.vim/after/ftplugin/fortan.vim

What does

:set formatexpr?:set indentexpr?:set cindent?:set filetype?:set paste?:filetype

print.

At least one of those (and I think all of them) will override the setting for textwidth.

For example, if you're editing a C source file, the C indent rules override textwidth.