When designing steps with operations requiring variables, it is best practice to query targets for variables1.
This allows you to dynamically obtain the values of the variables from the target devices, rather than hard coding them or using scalar variables that may not reflect the current state of the target. Querying targets for variables also enables you to design for a dynamic environment, where the target configuration may change over time.
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1: Define discovery steps

The Pattern Designer in ServiceNow Discovery uses different types of horizontal patterns to model various IT components and services. The temporary variable 'computer_system' seen in the pattern indicates that this is a
'Computer System' pattern type. This type of pattern is used to model and discover details about computer systems, which typically include hardware, operating system, and other related components.

A horizontal discovery pattern is a series of operations that tell Discovery how to find and identify an application on a host1. To extract the build and version numbers from the config file, the pattern can use either of the following methods:
* Parse File operation with Delimited Text parsing strategy: This operation reads the content of a file and splits it into fields based on a delimiter character. The pattern can specify the delimiter as a space and the fields to extract as the second and fourth ones from the first line of the file2.
* Parse File operation with Regular Expression parsing strategy: This operation reads the content of a file and matches it against a regular expression. The pattern can specify the regular expression as app build (\d+\.\d+\.\d+\.\d+) version (\d+\.\d+) and the groups to extract as the first and second ones from the first line of the file2.
References:
* 1: Patterns and horizontal discovery - Product Documentation: Tokyo - ServiceNow
* 2: Parse File operation - Product Documentation: San Diego - ServiceNow