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Linode Instance Management and the cpuser_service_manager Script with Ubic Subsystem

This guide explains how to manage a Linode instance after deployment, including accessing the server, performing essential instance actions, and handling lifecycle operations. It also provides a complete overview of the cpuser_service_manager script and the Ubic subsystem, which allow cPanel users to manage user-level services efficiently.

Linode Instancecpuser_service_managerUbic Subsystem

~5 min read • Updated Feb 22, 2026

1. Overview


After creating an instance on Linode, you can manage it through the Linode Manager interface. This guide covers essential instance‑management tasks and explains how to use the cpuser_service_manager script and the Ubic subsystem for managing user‑level services in cPanel.


Warnings:

  • This guide assumes you already have a Linode account.
  • Linode refers to instances as “Linodes,” but this document uses the term “instance.”
  • You must purchase a cPanel & WHM license. New installations receive a free 15‑day trial.
  • cPanel & WHM cannot run on IPv6‑only servers. At least one IPv4 address is required.


2. Access Your Instance for the First Time


  1. Navigate to the Linode Login interface.
  2. Enter your username and password.
  3. From the left navigation bar, click Linodes.
  4. Click the label of the instance you want to access.

The instance profile displays statistics and available actions.


2.1 Locate IP Addresses


In the instance list, locate the public IPv4 and IPv6 addresses.


2.2 Access the Command Line


To open a console:

  • Click Launch LISH Console.

To access via SSH:

ssh -i "~/.ssh/example.pem" root@IPADDRESS

Log in as root using the root password. The system will display a Message of the Day with helpful links and a WHM login URL.


To log in to WHM:

https://IPADDRESS:2087

Accept the license agreement, enter your contact details and nameserver information, and proceed to the WHM Home interface.


To configure the hostname:

WHM » Networking Setup » Change Hostname


Important: Set the hostname before obtaining a cPanel & WHM license.



3. Manage Your Instances


Important: Stop unused instances to avoid unnecessary charges.


  1. Log in to Linode.
  2. Click Linodes.
  3. Click the three dots next to the instance.

3.1 Available Actions


  • Power On / Power Off — Start or stop the instance.
  • Reboot — Restart the instance.
  • Launch LISH Console — Open a terminal session.
  • Clone — Duplicate the instance.
  • Resize — Adjust CPU, RAM, and disk space.
  • Rebuild — Reinstall the instance.

Warning: Rebuilding permanently deletes all data.


  • Rescue — Boot into Rescue Mode.
  • Migrate — Move the instance to another region.

Important: Migration assigns new IPv4/IPv6 addresses. Update DNS and your cPanel license.


  • Delete — Permanently remove the instance.

Warning: Deleting an instance is irreversible.



4. The cpuser_service_manager Script


The cpuser_service_manager script allows cPanel users to add, remove, and monitor user‑managed services such as Tomcat, Rails, WSGI, and PSGI applications. It configures the Ubic subsystem and adds a watchdog cron job.


Run the script using:

/usr/local/cpanel/scripts/cpuser_service_manager [argument] [options]

4.1 Script Arguments


Argument Description Example
add service_name --init-script=path Add a user‑managed service using an LSB‑compliant script. /usr/local/cpanel/scripts/cpuser_service_manager add my_app --init-script=/path/to/init
add service_name --ubic-service=path Add a service using a Ubic‑compliant script. /usr/local/cpanel/scripts/cpuser_service_manager add my_app --ubic-service=/path/to/ubic
info Display script information. /usr/local/cpanel/scripts/cpuser_service_manager info
list List user‑managed services. /usr/local/cpanel/scripts/cpuser_service_manager list
remove service_name Remove a service. /usr/local/cpanel/scripts/cpuser_service_manager remove my_app
hint [argument] Show abbreviated help. /usr/local/cpanel/scripts/cpuser_service_manager hint add
help [argument] Show full help. /usr/local/cpanel/scripts/cpuser_service_manager help add


5. The Ubic Subsystem


The script configures the Ubic subsystem when adding a service. Ubic allows users to start, stop, restart, and check the status of their services.


Ubic adds the following to the account:

  • ~/ubic directory
  • ~/.ubic.cfg configuration file
  • A watchdog cron job

Important: Do not edit ~/.ubic.cfg.


5.1 Ubic Commands


Use Ubic with:

ubic [argument] [service_name]

Argument Description Example
status Show service status. ubic status my_app
start Start a service. ubic start my_app
stop Stop a service. ubic stop my_app
restart Restart a service. ubic restart my_app


Conclusion


This guide covers essential Linode instance‑management tasks and explains how to use the cpuser_service_manager script and Ubic subsystem to manage user‑level services. These tools provide powerful control over your applications and server environment.


Written & researched by Dr. Shahin Siami

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