Avamar: How to Use the Screen Program for Long-running Tasks
Summary: This article outlines the steps for using the screen utility to carry out tasks that SSH session timeouts may disrupt. By following these instructions, you can ensure that lengthy processes continue to run uninterrupted. ...
This article applies to
This article does not apply to
This article is not tied to any specific product.
Not all product versions are identified in this article.
Instructions
What is a screen in Linux?
Screen serves as a comprehensive window manager that enables multiple processes, interactive shells, to share a single physical terminal screen.
Its key advantage lies in its ability to detach processes, meaning that even if the initiating SSH session ends, the processes within the screen remain unaffected. This feature is useful for running long-running tasks without the danger of them being cut off due to SSH timeouts specified in the
Unlike running a process in the background with
For example, using
There are multiple ways of using screen. Below is an example of how the utility should be used in Avamar.
The
Example:
Note: The screen sessions inherit the privileges of the user that created a session. If the session is created as an admin user, it presents the admin user’s prompt upon creation. The sessions are isolated, and users cannot see the sessions created by other users - that is also true for the root user!
Within a screen session, run the command as if this was a standard SSH session. When the command is running, it is possible to leave the screen session using the key combination of
If the process came back to the command prompt and the intent is to leave the screen session running (not recommended), detach the current screen using:
The below commands can be used to list current sessions on the system:
How to re-connect to the running session.
The following command is used to re-connect to the session:
How to terminate the screen session.
From within the screen:
Screen serves as a comprehensive window manager that enables multiple processes, interactive shells, to share a single physical terminal screen.
Its key advantage lies in its ability to detach processes, meaning that even if the initiating SSH session ends, the processes within the screen remain unaffected. This feature is useful for running long-running tasks without the danger of them being cut off due to SSH timeouts specified in the
/etc/ssh/sshd_config file.
Unlike running a process in the background with
nohup, a screen provides the capability to interact with the process. This is essential in situations where input is required from the user, which would not be feasible with nohup.
For example, using
nohup would not be possible in the following scenario, because the script expects the input:
admin@ave-1:~/>: remove_ddr_backups --delete-backups ddrindex 1 remove_ddr_backups will irrevocably destroy backup data on server 'ave-1'. Type 'yes' to permanently remove backup data on this server:How to use screen in Avamar.
There are multiple ways of using screen. Below is an example of how the utility should be used in Avamar.
The
-S option should be used to specify the screen name. The best practice would be to use the Service Request number so that the session can be identified.
Example:
screen -S SR19150xxxxThis command opens the new screen session with the session name of SR19150xxxx with the command prompt.
Note: The
<PID.session_name> identifies the screen sessions, not just the session name alone. Because of that, the same session name can be used multiple times. If the session name is used multiple times, the screen -ls command lists all of them:
admin@ave-1:~/>: screen -ls There are screens on: 925.SR19150xxxx (Attached) 759.SR19150xxxx (Detached) 2 Sockets in /var/run/uscreens/S-admin.
Note: The screen sessions inherit the privileges of the user that created a session. If the session is created as an admin user, it presents the admin user’s prompt upon creation. The sessions are isolated, and users cannot see the sessions created by other users - that is also true for the root user!
Within a screen session, run the command as if this was a standard SSH session. When the command is running, it is possible to leave the screen session using the key combination of
Ctrl+AD, if required. If the session is left open, it remains open until it is terminated, even when the connection to the Avamar node times out.
If the process came back to the command prompt and the intent is to leave the screen session running (not recommended), detach the current screen using:
screen -dHow to list the running sessions.
The below commands can be used to list current sessions on the system:
screen -lsor
screen -list
Note: The commands only list the screen sessions for the current user. For example, running the command as the root user does not show sessions started by the admin user.
How to re-connect to the running session.
The following command is used to re-connect to the session:
screen -r <session_name>Example:
admin@ave-1:~/>: screen -ls
There is a screen on:
8349.SR19150xxxx (Detached)
1 Socket in /var/run/uscreens/S-admin.
admin@ave-1:~/>: screen -r 8349.SR19150xxxx
How to terminate the screen session.
From within the screen:
exitFrom outside of the screen:
screen -X <session_name> kill
Additional Information
For more information about the screen utility, check the Linux Manual 
Affected Products
Avamar ServerProducts
SUSE Linux Enterprise Server 12, SUSE Linux Enterprise Server 15Article Properties
Article Number: 000227271
Article Type: How To
Last Modified: 19 June 2025
Version: 4
Find answers to your questions from other Dell users
Support Services
Check if your device is covered by Support Services.