add(tmux): copy support for linux

[ghost]

As I couldn't test in mac I've left your commands the same but you can see here that there's no longer a need for reattach-to-user-namespace. You have to test if it works just with pbcopy alone.

An useful addition that I haven't included is that selection with mouse should copy to clipboard right away, in addition to the default action. In linux it's done with:

bind -T copy-mode-vi v send -X begin-selection

if-shell 'uname | grep -q Darwin' {
    bind C-c run 'tmux save-buffer - | reattach-to-user-namespace pbcopy'; \
    bind C-v run 'tmux set-buffer $(reattach-to-user-namespace pbpaste); tmux paste-buffer'
    bind -T copy-mode-vi y send -X copy-pipe-and-cancel 'tmux save-buffer - | reattach-to-user-namespace pbcopy'; \
    bind -T copy-mode-vi C-v send -X rectangle-toggle \; send -X begin-selection; \

    # Selection with mouse should copy to clipboard right away, in addition to the default action.
    unbind -n -T copy-mode-vi MouseDragEnd1Pane; \
    bind -T copy-mode-vi MouseDragEnd1Pane send -X copy-selection-and-cancel\; run 'tmux save-buffer - | reattach-to-user-namespace pbcopy > /dev/null'; \

    # Middle click to paste from the clipboard
    unbind MouseDown2Pane; \
    bind -n MouseDown2Pane run 'tmux set-buffer $(reattach-to-user-namespace pbpaste); tmux paste-buffer'
}

if-shell '[[ $(uname -s) = Linux ]]' {
    bind C-c run "tmux save-buffer - | xclip -selection clipboard -in"; \
    bind C-v run 'tmux set-buffer $(xclip -selection clipboard -out); tmux paste-buffer'; \
    bind -T copy-mode-vi y send -X copy-pipe-and-cancel 'xclip -selection clipboard -in'; \
    bind -T copy-mode-vi C-v send -X rectangle-toggle \; send -X begin-selection; \

\   # Selection with mouse should copy to clipboard right away, in addition to the default action.
    unbind -n -T copy-mode-vi MouseDragEnd1Pane; \
    bind -T copy-mode-vi MouseDragEnd1Pane send -X copy-selection-and-cancel\; run 'tmux save-buffer - | xclip -selection clipboard -in > /dev/null'; \

    # Middle click to paste from the clipboard
    unbind MouseDown2Pane; \
    bind -n MouseDown2Pane run 'tmux set-buffer $(xclip -o -sel clipboard); tmux paste-buffer'
}

[ghost]

Now that I think of it, maybe by just aliasing xclip to pbcopy on linux in the zshrc it would work with the same lines as in maxos:

alias pbcopy='xclip -selection clipboard -in'
alias pbpaste='xclip -selection clipboard -out'

[nicknisi]

I tested without reattach-to-user-namespace and it works well, so I removed that and pushed up. Fixed in dc09b2f. Thank you!