How to prevent Vim from clearing the system clipboard (:reg +) on exit?

Question

After copying text to the system keyboard clipboard in vim, I'm unable to paste the text after exiting vim.

I find this behavior frustrating, since I often copy text in files to paste it on the command-line, and this is currently not possible without opening two tabs in the terminal or using a terminal multiplexer (e.g. tmux).

" system clipboard: CLIPBOARD (+)
noremap <leader>y "+y

How can I prevent vim from clearing the system clipboard on exit?

vim --version:

$ vim --version
VIM - Vi IMproved 8.1 (2018 May 18, compiled Jun 15 2019 16:41:15)
Included patches: 1-875, 878, 884, 948, 1046, 1365-1368, 1382, 1401
Modified by [email protected]
Compiled by [email protected]
Huge version with GTK3 GUI.  Features included (+) or not (-):
+acl               +extra_search      +mouse_netterm     +tag_old_static
+arabic            +farsi             +mouse_sgr         -tag_any_white
+autocmd           +file_in_path      -mouse_sysmouse    +tcl
+autochdir         +find_in_path      +mouse_urxvt       +termguicolors
-autoservername    +float             +mouse_xterm       +terminal
+balloon_eval      +folding           +multi_byte        +terminfo
+balloon_eval_term -footer            +multi_lang        +termresponse
+browse            +fork()            -mzscheme          +textobjects
++builtin_terms    +gettext           +netbeans_intg     +textprop
+byte_offset       -hangul_input      +num64             +timers
+channel           +iconv             +packages          +title
+cindent           +insert_expand     +path_extra        +toolbar
+clientserver      +job               +perl              +user_commands
+clipboard         +jumplist          +persistent_undo   +vartabs
+cmdline_compl     +keymap            +postscript        +vertsplit
+cmdline_hist      +lambda            +printer           +virtualedit
+cmdline_info      +langmap           +profile           +visual
+comments          +libcall           -python            +visualextra
+conceal           +linebreak         +python3           +viminfo
+cryptv            +lispindent        +quickfix          +vreplace
+cscope            +listcmds          +reltime           +wildignore
+cursorbind        +localmap          +rightleft         +wildmenu
+cursorshape       +lua               +ruby              +windows
+dialog_con_gui    +menu              +scrollbind        +writebackup
+diff              +mksession         +signs             +X11
+digraphs          +modify_fname      +smartindent       -xfontset
+dnd               +mouse             +startuptime       +xim
-ebcdic            +mouseshape        +statusline        +xpm
+emacs_tags        +mouse_dec         -sun_workshop      +xsmp_interact
+eval              +mouse_gpm         +syntax            +xterm_clipboard
+ex_extra          -mouse_jsbterm     +tag_binary        -xterm_save
   system vimrc file: "$VIM/vimrc"
     user vimrc file: "$HOME/.vimrc"
 2nd user vimrc file: "~/.vim/vimrc"
      user exrc file: "$HOME/.exrc"
  system gvimrc file: "$VIM/gvimrc"
    user gvimrc file: "$HOME/.gvimrc"
2nd user gvimrc file: "~/.vim/gvimrc"
       defaults file: "$VIMRUNTIME/defaults.vim"
    system menu file: "$VIMRUNTIME/menu.vim"
  fall-back for $VIM: "/usr/share/vim"
Compilation: gcc -c -I. -Iproto -DHAVE_CONFIG_H -DFEAT_GUI_GTK  -pthread -I/usr/include/gtk-3.0 -I/usr/include/at-spi2-atk/2.0 -I/usr/include/at-spi-2.0 -I/usr/include/dbus-1.0 -I/usr/lib/x86_64-linux-gnu/dbus-1.0/include -I/usr/include/gtk-3.0 -I/usr/include/gio-unix-2.0 -I/usr/include/cairo -I/usr/include/libdrm -I/usr/include/pango-1.0 -I/usr/include/harfbuzz -I/usr/include/pango-1.0 -I/usr/include/fribidi -I/usr/include/atk-1.0 -I/usr/include/cairo -I/usr/include/pixman-1 -I/usr/include/freetype2 -I/usr/include/libpng16 -I/usr/include/gdk-pixbuf-2.0 -I/usr/include/libmount -I/usr/include/blkid -I/usr/include/uuid -I/usr/include/glib-2.0 -I/usr/lib/x86_64-linux-gnu/glib-2.0/include -Wdate-time  -g -O2 -fdebug-prefix-map=/build/vim-4Pursk/vim-8.1.0875=. -fstack-protector-strong -Wformat -Werror=format-security -U_FORTIFY_SOURCE -D_FORTIFY_SOURCE=1
Linking: gcc   -L. -Wl,-z,relro -Wl,-z,now -fstack-protector -rdynamic -Wl,-export-dynamic -Wl,-E  -Wl,-z,relro -Wl,-z,now -Wl,--as-needed -o vim   -lgtk-3 -lgdk-3 -lpangocairo-1.0 -lpango-1.0 -latk-1.0 -lcairo-gobject -lcairo -lgdk_pixbuf-2.0 -lgio-2.0 -lgobject-2.0 -lglib-2.0 -lSM -lICE -lXpm -lXt -lX11 -lXdmcp -lSM -lICE  -lm -ltinfo -lnsl  -lselinux  -lacl -lattr -lgpm -ldl  -L/usr/lib -llua5.2 -Wl,-E  -fstack-protector-strong -L/usr/local/lib  -L/usr/lib/x86_64-linux-gnu/perl/5.28/CORE -lperl -ldl -lm -lpthread -lcrypt  -L/usr/lib/python3.7/config-3.7m-x86_64-linux-gnu -lpython3.7m -lcrypt -lpthread -ldl -lutil -lm -L/usr/lib/x86_64-linux-gnu -ltcl8.6 -ldl -lz -lpthread -lm -lruby-2.5 -lpthread -lgmp -ldl -lcrypt -lm

Answer 1

Solution

Install a clipboard manager.

For example, I use clipmenu. I start it whenever X is started by putting this

CM_OWN_CLIPBOARD=1 clipmenud &

in my ~/.xinitrc.

Why

Yours is a common misunderstanding when talking about X selections.

From Arch Wiki: Clipboard:

According to the selection protocols, nothing is copied until it is pasted. For example, if you select some word in a terminal window, close the terminal and then want to paste it somewhere else, it will not work because the terminal is gone and the text has not been copied anywhere. If you want the word to be preserved after closing terminal window, consider installing a clipboard manager.

From Ubuntu Wiki: ClipboardPersistence:

The problem happens because Xorg takes a conservative approach to copying. It copies only a reference to the original data when the user performs a select or copy. It doesn't go and retrieve the actual data from the source program until the user requests a paste. It saves a lot of unneeded transfer of data this way, at the expense of having no way of retrieving data from a closed program that hasn't saved its clipboard somewhere else.