(command -v tmux>/dev/null)- Tmux is installed
[[ ! $TERM =~ screen ]] && [ -z $TMUX ]- try not to run Tmux inside Tmux
[ "$TMUX_ENABLED" == "yes" ]- TMUX_ENABLED is set from Alacritty config file and it will start Tmux only in this terminal emulator.
tmux new -s 0- find or duplicate a session with name 0
tmux attach -t 0- attach to session 0