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GNU Screen terminal emulation

DESCRIPTION

Screen is a full-screen window manager that multiplexes a physical terminal between several processes (typically interactive shells).

SYNOPSIS

       screen [ -options ] [ cmd [ args ] ]
       screen -r [[pid.]tty[.host]]
       screen -r sessionowner/[[pid.]tty[.host]]

You need to have screen installed check for. /usr/bin/screen
Install if not found. yum install screen
When screen is called, it creates a single window with a shell.
By default, each command begins with a control-a (abbreviated C-a from now on), and is followed by one other keystroke.
The standard way to create a new window is to type "C-a c" where C= ctrl key

Getting Started with screen for the first time.

Step 1 create fresh screen session:

screen -S <Yourname>

-S sessionname

When creating a new session, this option can be used to specify a meaningful name for the session.

This name identifies the session for "screen -list" and "screen -r" actions. It substitutes the default [tty.host] suffix.

The first window (the one you're actually using) is numbered as 0, while future windows will be labeled as 1, 2, 3 etc.

Step 2 create a new window.

Ctrl+a and then press c (create).

Press Ctrl+a, then n to switch to next window and Ctrl+a, then n to switch to the previous one.

List the window created.

Press Ctrl+a, and then Shift+" to see the list.
Press Ctrl+a, then a number from 0 to 9, to switch to the corresponding window.

Step 3 To detach from this session, press

Ctrl+a d.

Step 4 To kill not responding programs, use

Ctrl+a K.

Step 5 To see the screen sessions created.

screen -list

Step 6 To re-attach to a detached session, open a terminal and type.

screen -r <session>

Step 7 Sharing a screen session

Set the screen binary setuid root.

chmod +s /usr/bin/screen

screen -S sessionName

Enable screen's multi-user access function by pressing Ctrl+a then :multiuser on (to type ":", press "shift+;")
Grant permissions to the second user by pressing

Ctrl+a: acladd username, where username is the Unix user for the second user.

User can now connect.

screen -x sessionName

Step 8 To scroll back through screen's history.

Enable the copy mode by pressing Ctrl+a [
Now, use either one of the arrow keys, page up, page down, home and end keys to scroll through screen's history.
Pressing Enter will start marking text for copying.
Pressing Enter again will copy the selected text into the clipboard. Now, to paste that text, press Ctrl+a ].

Step 9 To split the screen in two

First create two screen sessions.
Press Ctrl+a S which will split the screen in half.
To move to the bottom half, press Ctrl+a, then the TAB key.
Next press Ctrl+a, then " (shift+'). You will be presented with a list of available screen sessions
To Go back before the split press Ctrl+a Q.

Step 10 Help within Screen.

Ctrl+a ? shows the key bindings

Screen key bindings, page 1 of 2.

                       Command key:  ^A   Literal ^A:  a

   break      ^B b          lockscreen ^X x          reset      Z
   clear      C             log        H             screen     ^C c
   colon      :             login      L             select     '
   copy       ^[ [          meta       a             silence    _
   detach     ^D d          monitor    M             split      S
   digraph    ^V            next       ^@ ^N sp n    suspend    ^Z z
   displays   *             number     N             time       ^T t
   fit        F             only       Q             title      A
   flow       ^F f          other      ^A            vbell      ^G
   focus      ^I            pow_break  B             version    v
   help       ?             pow_detach D             width      W
   history    { }           prev       ^P p ^?       windows    ^W w
   info       i             readbuf    <             wrap       ^R r
   kill       K             redisplay  ^L l          writebuf   >
   lastmsg    ^M m          remove     X             xoff       ^S s
   license    ,             removebuf  =             xon        ^Q q

^]  paste [.]
"   windowlist -b
-   select -
0   select 0
1   select 1
2   select 2
3   select 3
4   select 4
5   select 5
6   select 6
7   select 7
8   select 8
9   select 9
I   login on
O   login off
]   paste .

Step 11 Help from command help.

Use: screen [-opts] [cmd [args]]
 or: screen -r [host.tty]

Options:
-a            Force all capabilities into each window's termcap.
-A -[r|R]     Adapt all windows to the new display width & height.
-c file       Read configuration file instead of '.screenrc'.
-d (-r)       Detach the elsewhere running screen (and reattach here).
-dmS name     Start as daemon: Screen session in detached mode.
-D (-r)       Detach and logout remote (and reattach here).
-D -RR        Do whatever is needed to get a screen session.
-e xy         Change command characters.
-f            Flow control on, -fn = off, -fa = auto.
-h lines      Set the size of the scrollback history buffer.
-i            Interrupt output sooner when flow control is on.
-l            Login mode on (update /var/run/utmp), -ln = off.
-list         or -ls. Do nothing, just list our SockDir.
-L            Turn on output logging.
-m            ignore $STY variable, do create a new screen session.
-O            Choose optimal output rather than exact vt100 emulation.
-p window     Preselect the named window if it exists.
-q            Quiet startup. Exits with non-zero return code if unsuccessful.
-r            Reattach to a detached screen process.
-R            Reattach if possible, otherwise start a new session.
-s shell      Shell to execute rather than $SHELL.
-S sockname   Name this session <pid>.sockname instead of <pid>.<tty>.<host>.
-t title      Set title. (window's name).
-T term       Use term as $TERM for windows, rather than "screen".
-U            Tell screen to use UTF-8 encoding.
-v            Print "Screen version 4.00.02 (FAU) 5-Dec-03".
-wipe         Do nothing, just clean up SockDir.
-x            Attach to a not detached screen. (Multi display mode).
-X            Execute <cmd> as a screen command in the specified session.

How to split the terminal into more than one “view”?

Example:

Ctrl+A then c creates a new window.
Ctrl+A then A sets the name of the current window.
Ctrl+A then a digit from 0 to 9 switches to that window.
Ctrl+A then " displays a list of all windows.
Ctrl+A then S splits the current window in two.
Ctrl+A then Ctrl+I changes the focus to the next window.
Ctrl+A then x locks Screen (much like a screensaver).
Ctrl+A then d detaches from the current Screen session.

.screenrc file in our home directory:

cd;vi .screenrc

Add the following two lines, keeping in mind that everything after the first line (bind X remove) is one single line:

bind X remove
hardstatus alwayslastline '%{= G}[ %{G}%H %{g}][%= %{= w}%?%-Lw%?%{= R}%n*%f %t%?%{= R}(%u)%?%{= w}%+Lw%?%= %{= g}][ %{y}Load: %l %{g}][%{B}%Y-%m-%d %{W}%c:%s %{g}]'

Save and exit.

GNU-Screen