tmux is super handy for long running commands. Especially if you have a dodgy connection which is likely to break: the command will keep running and you can re-attach to the session to save the day.
But as a dyed-in-the-wool bash user, I've kinda got used to being able to scroll up and down my command history and copy items from there. But I always have to search the internet the exact commands I need in tmux. Here's an easy way to dump the whole tmux history buffer to a text file without complicated edit/scroll/copy start/copy end combinations. We'll assume your tmux prefix key is the default CTRL-B
CTRL-B : # default prefix key and colon. opens the command pane, at the bottom
capture-pane -S - # send whole history to tmux buffer
CTRL-B : # get ready for another command, tmux
save-buffer ~/tmux_output.txt # self explanatory Now you can use your text editor to look at the command history, alerts, and outputs. I had to use this recently when I piped a long running script through tee -a but it failed to send any of the screen output to the specified text file. This was a lifesaver.