Source: This discussion.

This allows you to scroll in tmux, and copy stuff by highlighting it with your mouse.


First create a tmux config file

touch ~/etc/tmux.conf

Then add the following text in the file you just created with preferred text editor (different config setup for mac)

# Linux only
set -g mouse on
bind -n WheelUpPane if-shell -F -t = "#{mouse_any_flag}" "send-keys -M" "if -Ft= '#{pane_in_mode}' 'send-keys -M' 'select-pane -t=; copy-mode -e; send-keys -M'"
bind -n WheelDownPane select-pane -t= \; send-keys -M
bind -n C-WheelUpPane select-pane -t= \; copy-mode -e \; send-keys -M
bind -T copy-mode-vi    C-WheelUpPane   send-keys -X halfpage-up
bind -T copy-mode-vi    C-WheelDownPane send-keys -X halfpage-down
bind -T copy-mode-emacs C-WheelUpPane   send-keys -X halfpage-up
bind -T copy-mode-emacs C-WheelDownPane send-keys -X halfpage-down
 
# To copy, left click and drag to highlight text in yellow, 
# once you release left click yellow text will disappear and will automatically be available in clibboard
# # Use vim keybindings in copy mode
setw -g mode-keys vi
# Update default binding of `Enter` to also use copy-pipe
unbind -T copy-mode-vi Enter
bind-key -T copy-mode-vi Enter send-keys -X copy-pipe-and-cancel "xclip -selection c"
bind-key -T copy-mode-vi MouseDragEnd1Pane send-keys -X copy-pipe-and-cancel "xclip -in -selection clipboard"

FInally, reset the tmux server

tmux kill-server