Ubuntu18.04取消VIM自动备份文件

方式一：

# ls
111.c  111.c~

例如：111.c~：备份文件。

# sudo cp /usr/share/vim/vim80/vimrc_example.vim /usr/share/vim/vim80/.vimrc.vim
# sudo vim /usr/share/vim/vim80/.vimrc.vim
if has("vms")
  set nobackup          " do not keep a backup file, use versions instead
else
  set backup           " keep a backup file (restore to previous version)
  if has('persistent_undo')
    set undofile        " keep an undo file (undo changes after closing)
  endif
endif

修改为：
if has("vms")
  set nobackup          " do not keep a backup file, use versions instead
else
//注释掉下一行
-  "set backup           " keep a backup file (restore to previous version)
  if has('persistent_undo')
    set undofile        " keep an undo file (undo changes after closing)
  endif
endif

方式二：

//关闭备份
# set nobackup

//打开备份
# set backup