1 config files in 39 etc 39 need updating
Use Table 9.6, “Comparison of Sys V Runlevels with systemd Targets” to map these runlevels to equivalent systemd targets.Then list these targets in the was previously started in runlevels 2, 3, 4, and 5, which translates to multi-user.target and graphical.target on Red Hat Enterprise Linux 7.On the other hand, if you intend just to modify or extend the behavior of an existing unit, use the instructions from Section 9.6.4, “Modifying Existing Unit Files”.The following procedure describes the general process of creating a custom service: text editor, it is often faster and more convenient to have it running in the background instead of starting a new instance of the program whenever editing a file.– wildcard strings that are dynamically replaced with unit parameters when the unit file is loaded.This enables creation of generic unit files that serve as templates for generating instantiated units.Converting an init script to a unit file requires analyzing the script and extracting the necessary information from it.Based on this data you can create a unit file as described in Section 9.6.2, “Creating Custom Unit Files”.
There are several use cases for creating unit files from scratch: you could run a custom daemon, create a second instance of some existing service (as in Example 9.19, “Creating a second instance of the sshd service”), or import a Sys V init script (more in Section 9.6.3, “Converting Sys V Init Scripts to Unit Files”).
See Section 9.6.5, “Working with Instantiated Units” for details.
A whole range of options that can be used to fine tune the unit configuration, Example 9.17, “postfix.service Unit File” shows an example of a service unit installed on the system.
The following steps show how to create a unit file for Emacs, so that it can be handled like a service.
System Administrators often need to configure and run multiple instances of a service.
The symbolic links are automatically created either during installation according to [Install] unit file options (see Table 9.11, “Important [Install] Section Options”) or at runtime based on [Unit] options (see Table 9.9, “Important [Unit] Section Options”).