When using Vim to edit a read only file it will just provide a warning the first time it is edited but allow any changes to take place. I can understand this behaviour could be useful for someone intending on saving the file under another name; but I sometimes open files that I don't have write access to, then forget and make changes.
Is it possible to enter a mode where Vim will allow the file to be viewed but block any option that makes changes?
I found a solution. Setting nomodifiable prevents the file being edited (as used in help windows). I created a simple function to set or unset modifiable depending on if readonly is set and attached it to an autocmd.
" Don't allow editing of read only files
autocmd BufRead * call RONoEdit()
function! RONoEdit()
if &readonly == 1
set nomodifiable
else
set modifiable
endif
endfunction
let &modifiable = !&readonly
May 29, 2015 at 9:10
autocmd BufRead * let &modifiable = !&readonly
May 29, 2015 at 15:11
readonly file and then creating a new buffer the new buffer ends up nomodifiable.
Jul 24, 2015 at 5:13
Add this to your .vimrc:
augroup NoModWhenReadOnly
autocmd!
autocmd BufRead * let &l:modifiable = !&readonly
augroup END
As much as the answers above are correct, there is another thing to take into account: as long as the file is "read-only", there should be no way of changing the file's content unless you're the owner of the file or have the right to make that file writable. And even then vim doesn't write changes to the file unless you explicitly override the "read-only" state by ":w!".
If you can in fact edit a file which is supposed to be read-only, you may want to recheck the rights, there may be a security misconfiguration. If you only make vim unable to edit the file, other ways of editing will still be in place so if the file is not to be changed, it should have the rights set properly. In windows, you can force the file to be read-only by explicitly denying the change right to everyone, in Linux you can use the "immutable" extended attribute (chattr +i).
