I'm trying to understand and eventually fix the following behavior: when I save a file using VIM, it triggers the change/write event twice.

I'm using Ubuntu 16.10, and I created an empty .vimrc file to make sure that no plugins create this behavior.

So, I open the foo.txt file:

vim -u .vimrc foo.txt

And then using inotify-tools (installed using sudo apt install inotify-tools) I run the following command:

inotifywait -m foo.txt

Then in VIM I do :w, triggering the save. I can see the following output:

$ inotifywait -m foo.txt 
Setting up watches.
Watches established.
foo.txt OPEN 
foo.txt ACCESS 
foo.txt MODIFY 
foo.txt OPEN 
foo.txt MODIFY 
foo.txt ATTRIB 

After setting backupcopy=yes I can see EXACTLY the same behavior. I tried to add it in the vimrc and restart VIM, but there was no change at all.

How can I fix this?

Everyone on the internet recommends using backupcopy=yes which for some reason doesn't fix the issue on my machine. Why?

Is there any other workaround?

In my original ~/.vimrc I do have this at the end of the file:

" Node.js fs.watch
set backupdir=~/.vim/tmp,.
set directory=~/.vim/tmp,.
set backupcopy=yes

Doesn't seem to make any change (I do have the ~/.vim/tmp dir).

  • Did you set backup as well? – laktak Mar 3 '17 at 20:02
  • @laktak Not sure about the backup you're mentioning, but I do have backupdir and directory, see the edit. – Ionică Bizău Mar 4 '17 at 19:29

If you have backupcopy=no Vim will try to rename the file. If this fails it will work the same way as backupcopy=yes.

For example (with strace):

rename("test.txt", "/tmp/test.txt~") = -1 EXDEV (Invalid cross-device link)

But in any case, Vim will only write to the file once:

set backupcopy=no

rename("test.txt", "test.txt~")   = 0
open("test.txt", O_WRONLY|O_CREAT|O_TRUNC, 0644) = 3
write(3, "a\nbb\n\nccc\ndddd\n\neeeee\n", 22) = 22
close(3)                                = 0

set backupcopy=yes

open("test.txt", O_RDONLY)           = 3
open("test.txt~", O_WRONLY|O_CREAT|O_EXCL|O_NOFOLLOW, 0644) = 5
read(3, "a\nbb\n\nccc\ndddd\n\neeeee\n", 8192) = 22
write(5, "a\nbb\n\nccc\ndddd\n\neeeee\n", 22) = 22
read(3, "", 8192)                       = 0
close(5)                                = 0
close(3)                                = 0
open("test.txt", O_WRONLY|O_CREAT|O_TRUNC, 0644) = 3
write(3, "a\nbb\n\nccc\ndddd\n\neeeee\n", 22) = 22
close(3)                                = 0

Maybe you have a plugin/autocmd that is responsible for the second write. Test with vim -u NONE.

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