Why does Git write to my files?

Question

I have a few source files in a Git repo, main.c and some others. I use Vim to edit these files.

Say I'm editing main.c . I make a change, tell Vim to write-out, then switch to a terminal (without killing Vim) and commit/push. If I go back to Vim with main.c and try to write-out again, I receive this warning:

WARNING: The file has been changed since reading it!!!
Do you really want to write to it (y/n)?

How does committing/pushing modify my source files? Why?

Answer 1

It could be a permission issue (git changing the executable bit of the file).
Try again after git config core.filemode false .

The solution is simple: reopen the file with :e filename .
Or (if your files are save and have no current modification), run :bufdo e , which will make Vim reopen every buffer.

Answer 2

Can you show us your .gitattributes file? Are you telling it to change the line endings?

Why don't you try doing a diff and showing us what the differences are.

Answer 3

The other answers have shown that the write may be due to Git performing a line ending change, or expands configured attributes. A simple solution is to

:set autoread

in Vim, to automatically update the file (as long as you haven't changed it, which based on your use case seems unlikely).

 'autoread' 'ar' boolean (default off) When a file has been detected to have been changed outside of Vim and it has not been changed inside of Vim, automatically read it again.