Getting tmux to accept "Shift+Return"

This is a very short post, but it's been too good not to share!

For a while now, I have been fighting with tmux. Every now and again, I try to create a new line in my terminal with "Shift+Return", and every time, tmux ignores me outright.

It was manageable for a while, but as I have been starting to use opencode more and more, the lack of a good, dedicated "make a new line" option in tmux was really starting to get to me. I was honestly mostly worried that I would have to give up my beloved tmux!

Well, I will worry no longer! I found a solution, and let me tell you, it's incredibly simple and has made a massive difference in my daily developer life.

Here's the trick:

In your tmux configuration file, add this one little line:

set -s extended-keys on

With this little configuration, we now tell tmux that it is ok to pass "Shift+Return" through to the underlying terminal instance.

Full disclosure: apparently tmux has this feature enabled by default in versions >= 3.5. However, I am currently running tmux 3.6 and I still had to manually add this line to my configuration files. It's very likely an issue between my chair and my keyboard, but truly, it doesn't matter--I'm just pleased as punch that I can pass through my "give me a new line" key combo and start writing massive walls of multi-paragraph text to my AI assistants!

Find this helpful, or know of any other cool tmux tips and tricks? Hit me up on Twitter or Bluesky and let me know!

Happy muxxing!