Scrolling on Mac with Tmux and iTerm
Solution 1:
Tmux scrolling is a little different than just scrolling with a mouse wheel or a trackpad.
In tmux, scrolling is accomplished by first sending 'prefix-['. You'll see a little yellow box in the upper, right-hand corner of your terminal window.
In this mode, you can use arrow keys, PageUp, PageDown, Ctrl-U, Ctrl-D, hjkl (vi-mode), or other configurable movement keys to scroll forward or back through the buffer.
There is an option in relatively recent builds of tmux that allows you to use the mouse while in scrolling mode.
add this to your .tmux.conf
set-option -g mouse on
Additionally, if memory serves, tmux is 'built into' iTerm, and thus features like multiplexing are built in as well. Is there a reason you want to use tmux in iTerm? The built-in OSX Terminal is definitely enhanced by a multiplexer like tmux, but iTerm seeks to alleviate those shortcomings by being a standalone solution.
EDIT 1: After upgrading to El Capitan, I noticed some unfamiliar behavior when using Terminal.app and tmux. This led me to an excellent article detailing options I wasn't aware of and which look to answer your question more thoroughly than I could hope to. All the options are tmux-specific, as far as I can tell, and are independent of OSX versions, so using them in Yosemite should be fine. Your scrolling question is covered here, with options like:
bind-key -t vi-copy WheelUpPane scroll-up
bind-key -t vi-copy WheelDownPane scroll-down
Many more useful options in the article linked below.
https://ryanfb.github.io/etc/2015/10/19/tmux_mouse_mode_on_el_capitan.html
Solution 2:
I found following ways to deal with it (macOS Mojave):
Enable tmux scroll mode and then press arrow up key; iTerm prompts you to set the aforementioned preference for scrolling. But in case you missed/dismissed this prompt you won't be prompted again, I think.
Go to iTerm settings -> "Advanced" -> "Scroll wheel sends arrow keys when in alternate screen mode" -> set to "yes".
Solution 3:
Met the issue these days. Env:
MacOS Big Sur 11.4
iTerm2 build 3.4.8
Tried
set-option -g mouse on
and only works in ctrl + b + [
mode.
Mouse scroll still shows the history message in normal mode.
Finally I found press Opt + mouse Scroll works only if there is no tmux split window.