Wide terminals have room for two shells without switching back and forth between windows. In tmux, a vertical pane split uses that width to place two panes side by side.
The split direction in tmux names can be confusing. The default Ctrl-b % shortcut runs split-window -h to create left and right panes, even though their divider is vertical; split-window -v creates panes stacked above and below each other.
The shortcuts require an attached tmux session with the default Ctrl-b prefix and key bindings. The original pane must be at a shell prompt so both shells can accept commands after the split.
Steps to split a pane vertically in tmux:
- Press Ctrl-b followed by % in the pane to split.
The prefix and % are separate key presses; % is Shift-5 on a US keyboard. A new pane opens on the right and receives keyboard input. If tmux reports that there is no space for another pane, a larger terminal window provides more room.
- Run pwd in the new right pane to check that its shell accepts commands.
$ pwd /home/user
The output is the new shell's working directory; the path on your system may differ.
- Move focus back to the original left pane with Ctrl-b Left.
The cursor moves left while the right pane's output stays visible. Ctrl-b Right selects the right pane again when needed.
- Run pwd in the left pane to confirm that both shells remain usable side by side.
$ pwd /home/user
Two prompts separated by a vertical divider, with each pane retaining its own command output, show the split is ready for work.