if set -q TMUX
  set -l name (tmux display -p '#{session_name}')
  if test -n "$name"; and string match -qr '^[0-9]+' -- $name
    set num (string match -rim 1 "[0-9]*" -- $name)
    tmux rename-session "$num: cmd: $argv[1]" 2>/dev/null
  end
end