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
# default prefix key and colon. opens the command pane, at the bottom
CTRL-B :
# send whole history to tmux buffer
capture-pane -S -
# get ready for another command, tmux
CTRL-B :
# self explanatorysave-buffer ~/tmux_output.txt
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.