Sample script to start a tmux session with a vertically split window

tmux.sh

#!/bin/bash
SESSION=$USER

tmux -2 new-session -d -s $SESSION

# Setup a window
tmux new-window -t $SESSION:1 -n 'The Internet'

# Split the window vertically
tmux split-window -v
tmux select-pane -t 0
tmux send-keys "echo pane numero 1" C-m

tmux select-pane -t 1
tmux send-keys "echo pane numero 2" C-m