Linux: Screen Command

Getting in test
start a new screen session with session name 	screen -S <name>
list running sessions/screens 	screen -ls
attach to a running session 	screen -x
attach to session name 	screen -r <name>
the “ultimate attach” 	screen -dRR (Attaches to a screen session. If the session is attached elsewhere, detaches that other display. If no session exists, creates one. If multiple sessions exist, uses the first one.)
Escape key

All screen commands are prefixed by an escape key, by default C-a (that's Control-a, sometimes written ^a). To send a literal C-a to the programs in screen, use C-a a. This is useful when working with screen within screen. For example C-a a n will move screen to a new window on the screen within screen.
Getting out
detach 	C-a d
detach and logout (quick exit) 	C-a D D
exit screen 	C-a \ Exit all of the programs in screen. (not recommended)
force-exit screen 	C-a C-\ (not recommended)
getting out of the screen session 	exit
Window Management
create new window 	C-a c
change to last-visited active window 	C-a C-a (commonly used to flip-flop between two windows)
change to window by number 	C-a <number> (only for windows 0 to 9)
change to window by number or name 	C-a ' <number or title>
change to next window in list 	C-a n or C-a <space>
change to previous window in list 	C-a p or C-a <backspace>
see window list 	C-a " (allows you to select a window to change to)
show window bar 	C-a w (if you don't have window bar)
close current window 	Close all applications in the current window (including shell)
kill current window 	C-a k (not recommended)
kill all windows 	C-a \ (not recommended)
rename current window 	C-a A
Split screen
split display horizontally 	C-a S
split display vertically 	C-a | or C-a V (for the vanilla vertical screen patch)
jump to next display region 	C-a tab
remove current region 	C-a X
remove all regions but the current one 	C-a Q
Clipboard and Navigation
freely navigate buffer 	C-a [ or C-a <esc>
toggle selection to copy 	space
paste 	C-a ]
Help
See help 	C-a ? (lists keybindings)

The man page is the complete reference.
Scripting

To any session name,
send a command to a named session 	screen -S <name> -X <command>
create a new window and run ping example.com 	screen -S <name> -X screen ping example.com
stuff characters into the input buffer
using bash to expand a newline character
(from here) 	

screen -S <name> [-p <page>] -X stuff $'quit\r'

A full example:

# run bash within screen
screen -AmdS bash_shell bash
# run top within that bash session
screen -S bash_shell -p 0 -X stuff $'top\r'
 
# ... some time later
 
# stuff 'q' to tell top to quit
screen -S bash_shell -X stuff 'q'
# stuff 'exit\n' to exit bash session
screen -S bash_shell -X stuff $'exit\r'

Misc
redraw window 	C-a C-l
monitor window for activity 	C-a M
monitor window for silence 	C-a _
enter digraph (for producing non-ASCII characters) 	C-a C-v
lock (password protect) session 	C-a x
enter screen command 	C-a :
enable logging in the screen session 	C-a H
Scrollback-buffer

In copy mode, one can navigate the scrollback buffer in various ways:
half page up 	C-u 		half page down 	C-d
back 	C-b 		forward 	C-f
cursor left/down/up/right 	h/j/k/l 

Other Examples:
screen -AmdS bash_shell bash ; screen -S bash_shell -p 0 -X stuff $'yum update -y\r' ; screen -S bash_shell -p 0 -X stuff $'exit\r'
screen -AmdS bash_shell bash ; screen -S bash_shell -p 0 -X stuff $'yum update -y\r' ; screen -S bash_shell -p 0 -X stuff $'reboot\r'