How to use Devstack screen (log of all openstack services)

1)
Open the screen
screen -x

2)
Close the screen
Ctrl + a + d

3)
Move to Next service
Ctrl + a, n

4)
Move to previous service
Ctrl + a, p

5)
Scroll Up and Down
Ctrl + A, Esc, 'Up' and 'Down' arrow

6)
To stop logging of particular service
Ctrl + c
To start logging again use 'Up' arrow and select logging command and press Enter button.