How vim copies and pastes the entire content into the external

Ubuntu default installation of Vim is not supported by the system cut, paste version, you need to perform the following installation:
sudo apt-get install Vim-gnome

Note to allow VIM to support the system Pasteboard, first perform the sudo apt-get install Vim-gui-common installation to support system Clipboard vim.
--------------------------------------------------------------------------------------------------------------- ----------------------------------
PS: Whether the above two steps are to be confirmed (own computer virtual machine test: As long as the first command of the Vim-gnome version of Vim can be installed)

1. Cursor at the first character, press V to enter the visual mode
2.G, the cursor jumps to the end, automatically select all the contents
3. Press "+y, copy to system Clipboard
4. External Ctrl + V to paste it over

How vim copies and pastes the entire content into the external