I have found scrolling in tmux is a bit unconventional. Maybe its just me, but sometimes, the terminal interfaces are different, sometimes they are a bit wired, I use Ghostty right now, so selection without tmux works a charm, but the moment I am in tmux, ahmm, it kind of breaks.

The selection of text doesn't work with the mouse atleast, so I thought, I need a keyboard centric selection and copying mechanism, and dug in this rabit hole. Turns out, tmux is way better in selection then zellij, the multiplexer I had been using due to scroll and selection issues in terminal interfaces.

It's simple as Prefix + [ to enter the scroll mode, Shift+V or Ctrl+space or Ctrl+v to start the selection in different ways, and finally, Enter or Ctrl+j to copy to clipboard. There is a dedicated mode for vi users, to feel at home. Tmux + Vim again a deadly combo.

Entering Scroll Mode

To enter scroll mode, I had this config setup in my .tmux.conf file:

set -g mouse on

However if you want to enter without mouse on, you can use:

Ctrl + b + [

Here the Ctrl + b is for the prefix key, and [ is the key for enterring into the Scroll Mode

From here on you can use hjkl or arrow keys to scroll up or down.

To quit, you can press q or hit escape.

Selecting

Right now in scrolling mode, you can only navigate to the next or previous line.

But you can use Ctrl + <Space> to select any arbitrary sections of the terminal output. There are two modes in tmux for this the copy-mode i.e. the default, and the copy-mode-vi.

Without any config, this is be set to the default copy-mode, so we can use Ctrl + Space to begin selection in the scroll mode.

To get more keybindings for the copy-mode and copy-mode-vi, use

For copy-mode

tmux list-keys -T copy-mode

For copy-mode-vi

tmux list-keys -T copy-mode-vi

This is a default and can be over-written by using the following config:

setw -g mode-keys vi
unbind-key -T copy-mode-vi Space

# replace <your-key> with the key combination you want
bind-key -T copy-mode-vi <your-key> send-keys -X begin-selection

# Example: using ctrl + b + v as the key to start selection
# bind-key -T copy-mode-vi v send-keys -X begin-selection

This all would be applied to copy-mode if you are not changing the keybindings for copy-mode-vi.

Copying

Once, you have the selected region or piece of text, you can copy that to the clipboard (that is what you do, while logs-driven debugging :).

By default, you can use:

For copy-mode

• Ctrl + w

or

For copy-mode-vi

• Ctrl + j or Enter to copy the selected text to the clipboard.

This is default, and again can be over-written by using the following config:

setw -g mode-keys vi

bind-key -T copy-mode-vi <your-key> send-keys -X copy-pipe-and-cancel

# Example: Remap 'y' in copy-mode-vi to copy selection and exit
# bind-key -T copy-mode-vi y send-keys -X copy-pipe-and-cancel

This all would be applied to copy-mode if you are not changing the keybindings for copy-mode-vi.

That's it this should be more than enough for most of the log-driven or printf debugging tasks.