+ format for status-left - showing session name if presented

.tmux.conf

@@ -61,7 +61,9 @@ set -g status-bg default
 set -g status-fg white
 
 # Status bar - left side
-set -g status-left ''
+set -g status-left-length 50
+set -g status-left-style fg=white,bold,bg=blue
+set -g status-left '#(if [ "#S" -ge 0 ]; then echo "   "; else echo " #S "; fi)'
 
 # Status bar - right side
 set -g status-right-length 100