using screen to keep unix sessions active
In Unix, what is screen, and how do I use it?
The screen program allows you to use multiple windows (virtual VT100 terminals) in Unix.
Note: UITS does not support screen.
###Features###
- If your local computer crashes, or you are connected via a modem and lose the connection, the processes or login sessions you establish through screen don’t go away. You can resume your screen sessions with the following command:
screen -r
In some cases you may have to manually “detach” your screen session before resuming it. For more information, see the Knowledge Base document Using screen, why can’t I re-attach to my session after a lost connection?
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The screen program creates multiple processes instead of multiple Unix login sessions, which means that it is resource-efficient.
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You can cut and paste between different screens without using a mouse. Thus, you don’t need to be on a computer with a windowing environment such as Mac OS, Mac OS X, Windows, or the X Window System.
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It has a block copy feature which is similar to the kill rectangle feature of Emacs.
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You can copy and paste more than one page at a time, which you cannot do with some clients. You can scroll up more than one page, depending on how many scrolling lines you have set with the -h option.
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Using the detach feature, you can save screen processes when logging out and resume where you left off, saving the trouble of restarting them.
###Starting screen###
To start screen, enter the following command:
screen
###General commands###
Note: Every screen command begins with Ctrl-a .
Ctrl-a c |
Create new window (shell) |
Ctrl-a k
|
Kill the current window |
Ctrl-a w
|
List all windows (the current window is marked with "*") |
Ctrl-a 0-9
|
Go to a window numbered 0-9 |
Ctrl-a n
|
Go to the next window |
Ctrl-a Ctrl-a
|
Toggle between the current and previous window |
Ctrl-a [ |
Start copy mode |
Ctrl-a ] |
Paste copied text |
Ctrl-a ? |
Help (display a list of commands) |
Ctrl-a Ctrl-\ |
Quit screen
|
Ctrl-a D (Shift-d) |
Power detach and logout |
Ctrl-a d |
Detach but keep shell window open |
Press the Spacebar or Enter to end a command.
To copy a block
To get into copy mode, press Ctrl-a [ .
To move the cursor, press the h , j , k , and l (the letter l) keys. The 0 (the number 0) or ^ (the caret) moves to the start of the line and $ (the dollar sign) moves to the end of the line. Ctrl-b scrolls the cursor back one page and Ctrl-f scrolls forward one page. To set the left and right margins of copy, press c and C (Shift-c). The Spacebar starts selecting the text and ends selecting the text. To abort copy mode, press Ctrl-g .
To paste a block
To paste the copied text to the current window (as many times as you want), press Ctrl-a ] .
Other commands
To run a program or execute any Unix command in a new window, at the Unix prompt, enter:
screen unixcommand
Above, replace unixcommand with the appropriate command name.
To automatically start several windows when you run screen, create a .screenrc file in your home directory and put screen commands in it.
To quit screen (kill all windows in the current session), press Ctrl-a Ctrl-\ .
The man pages for screen are quite readable and make a good tutorial. At the Unix prompt, enter:
man screen
###[Source Link][http://kb.iu.edu/data/acuy.html]###
###If your unix server does not support screen. It is always a better to run some commands with nohup.###
Any questions on this, please feel free to ask. We’re here to help…