You can :set autoread
so that vim reads the file when it changes. However (depending on your platform), you have to give it focus.
From the help:
When a file has been detected to have
been changed outside of Vim and it
has not been changed inside of Vim,
automatically read it again. When the
file has been deleted this is not
done.
与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…