It seems that the clipboard variables mentioned by @Ehvince (which are useful BTW when working on GUI emacs) are not useful in terminals. A workaround is described here. I am adding the code in the article below, to avoid dead links
(unless window-system
(when (getenv "DISPLAY")
;; Callback for when user cuts
(defun xsel-cut-function (text &optional push)
;; Insert text to temp-buffer, and "send" content to xsel stdin
(with-temp-buffer
(insert text)
;; I prefer using the "clipboard" selection (the one the
;; typically is used by c-c/c-v) before the primary selection
;; (that uses mouse-select/middle-button-click)
(call-process-region (point-min) (point-max) "xsel" nil 0 nil "--clipboard" "--input")))
;; Call back for when user pastes
(defun xsel-paste-function()
;; Find out what is current selection by xsel. If it is different
;; from the top of the kill-ring (car kill-ring), then return
;; it. Else, nil is returned, so whatever is in the top of the
;; kill-ring will be used.
(let ((xsel-output (shell-command-to-string "xsel --clipboard --output")))
(unless (string= (car kill-ring) xsel-output)
xsel-output )))
;; Attach callbacks to hooks
(setq interprogram-cut-function 'xsel-cut-function)
(setq interprogram-paste-function 'xsel-paste-function)))
Add this your init file. You will need to install the an external program xsel
for this to work.