linux_wiki:screen

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linux_wiki:screen [2016/03/18 23:23]
billdozor [Screen] 		linux_wiki:screen [2019/05/25 23:50]
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-====== Screen ====== 
  
-**General Information** 
- 
-Screen is a "full-screen window manager that multiplexes a physical terminal between several processes". (screen man page) 
- 
-This allows you to have multiple virtual terminal "workspaces" within 1 actual terminal session. 
- 
-**Checklist** 
-  * Distro(s): Any 
-  * Package: screen 
- 
----- 
- 
-===== Install and Start ===== 
-<code bash> 
-yum install screen 
-or 
-apt-get install screen 
-</code> 
- 
-2) Start a screen session 
-<code bash> 
-screen -S MySession 
-</code> 
- 
-Screen may or may not show some startup dialog, but once you are past that, it will look just like a normal terminal prompt. 
- 
-3) To view a list of all key bindings: 
-<code bash> 
-Ctrl+a, then ? 
-</code> 
- 
-The listed commands have multiple ways of being executed. 
-You only have to press "Ctrl+a" and then the key letter for the desired action. 
-Press Space ore Enter to leave the help screen. 
- 
----- 
- 
-===== Some Examples ===== 
- 
-==== Creating and Moving Between Screens ==== 
- 
-Start top in one screen, create a new screen, and cycle between the two. 
- 
-Start top 
-<code bash> 
-top 
-</code> 
- 
-Create a new screen 
-<code bash> 
-Ctrl+a, then c 
-</code> 
- 
-You will be on the new screen session. Do something else to see the difference: 
-<code bash> 
-free -m 
-</code> 
- 
-Now, you can cycle between the two screen sessions by doing this: 
-<code bash> 
-Ctrl+a, then n 
-</code> 
- 
-You will notice that top was never interrupted, it was running the entire time on its screen session. 
- 
----- 
- 
-==== Detach and Reattach Screen ====  
- 
-The real power of screen is detaching a session and connecting back to it later. 
- 
-Detach scenarios: 
-  * Intentionally detach screen  
-  * Be working on a remote system and get a SSH/network interruption 
- 
-In either scenario, you can reconnect to your still running screen session without loosing any work. Perfect for long running processes or scripts. 
- 
-This can be demonstrated by executing a for loop that echos a number, sleeps for 1 second, and then keeps going. 
- 
-1) If it is not open still, start screen 
-<code bash> 
-screen -s MySession 
-</code> 
- 
-2) Start a long for loop...this should take about 5 minutes to complete. 
-<code bash> 
-for NUM in {1..300} 
-do echo -e "Number is: ${NUM}" 
-echo "Sleeping for 1 second..." 
-sleep 1 
-done 
-</code> 
- 
-3) Detach from screen after it has started. 
-<code bash> 
-Ctrl+a, then d 
-</code> 
- 
-4) List screen processes for your user. 
-<code bash> 
-screen -ls 
-</code> 
- 
-This will give you output similar to the following: 
-<code bash> 
-bill@dt-bill ~ $ screen -ls 
-There is a screen on: 
- 19734.MySession (03/09/2015 11:13:38 PM) (Detached) 
-1 Socket in /var/run/screen/S-bill. 
- 
-ps -ef | grep 19734 
-bill     19734     1  0 23:13 ?        00:00:00 SCREEN -S MySession 
-</code> 
- 
-You can see that the number is indeed a process ID. 
- 
-5) Reattach to the screen using the session name or process id: 
-<code bash> 
-screen -r MySession 
-or 
-screen -r 19734 
-</code> 
- 
-Note: You only have to specify the screen PID if you have multiple screen sessions detached and you are connecting to a specific one. (If only 1 screen session, you can just type "screen -r") 
- 
-You should find your still running for loop, chugging away. 
- 
----- 
- 
-==== Rename Existing Session ====  
- 
-If you started a new screen session without specifying a name or want to rename a session: 
- 
-1) Attach to your session 
-<code bash> 
-screen -r MySession 
-</code> 
- 
-2) Command Key, then colon 
-<code bash> 
-Ctrl+A : 
-</code> 
- 
-3) Type sessionname MyNewName, then enter 
-<code bash> 
-:sessionname MyNewName 
-</code> 
  • linux_wiki/screen.txt
  • Last modified: 2019/05/25 23:50
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