How to use the command "ffe" (with examples)

The “ffe” command is used to extract fields from a flat database file and write them to another format. It requires a configuration file to interpret the input and format the output. This command is particularly useful for managing and manipulating data in various formats.

Use case 1: Display all input data using the specified data configuration

Code:

ffe --configuration=path/to/config.ffe path/to/input

Motivation:

This use case is helpful when you want to view all the data in the input file with the specified data configuration. It can be used to verify that the input data is correctly interpreted and formatted according to the configuration.

Explanation:

• --configuration: Specifies the path to the configuration file that defines how to interpret the data in the input file.
• path/to/config.ffe: The path to the configuration file.
• path/to/input: The path to the input file.

Example output:

The command will display all the data from the input file according to the configuration specified in the configuration file.

Use case 2: Convert an input file to an output file in a new format

Code:

ffe --output=path/to/output -c path/to/config.ffe path/to/input

Motivation:

This use case is useful when you want to convert the data in a flat database file to a different format. You can specify the output file path and the command will use the configuration file to format the data accordingly.

Explanation:

• --output: Specifies the path to the output file.
• path/to/output: The path to the output file in the new format.
• -c: Specifies the configuration file to interpret the input data.
• path/to/config.ffe: The path to the configuration file.
• path/to/input: The path to the input file.

Example output:

The command will convert the data from the input file to the specified output file in the new format, using the configuration defined in the configuration file.

Use case 3: Select input structure and print format from definitions in ~/.fferc config file

Code:

ffe --structure=structure --print=format path/to/input

Motivation:

This use case is beneficial when you want to select a specific input structure and print the format from the definitions in the ~/.fferc configuration file. It allows you to quickly specify the desired structure and format without the need to write or modify a separate configuration file.

Explanation:

• --structure: Specifies the input structure to use from the definitions in the ~/.fferc configuration file.
• structure: The desired input structure defined in the ~/.fferc configuration file.
• --print: Specifies the format to print the data in.
• format: The desired format to print the data in.

Example output:

The command will use the specified input structure and print the data in the desired format from the input file.

Use case 4: Write only the selected fields

Code:

ffe --field-list="FirstName,LastName,Age" -c path/to/config.ffe path/to/input

Motivation:

This use case is useful when you only want to extract and write specific fields from the input file. It allows you to select which fields to include in the output, making it easier to work with a subset of the data.

Explanation:

• --field-list: Specifies the list of fields to include in the output.
• "FirstName,LastName,Age": The list of field names to include in the output, separated by commas.
• -c: Specifies the configuration file to interpret the input data.
• path/to/config.ffe: The path to the configuration file.
• path/to/input: The path to the input file.

Example output:

The command will write only the selected fields (FirstName, LastName, and Age) from the input file according to the configuration specified in the configuration file.

Use case 5: Write only the records that match an expression

Code:

ffe -e "LastName=Smith" -c path/to/config.ffe path/to/input

Motivation:

This use case is valuable when you want to filter the input data and extract only the records that match a specific expression. It allows you to focus on the relevant data and ignore irrelevant records.

Explanation:

• -e: Specifies the expression to match records against.
• "LastName=Smith": The expression to match records against.
• -c: Specifies the configuration file to interpret the input data.
• path/to/config.ffe: The path to the configuration file.
• path/to/input: The path to the input file.

Example output:

The command will write only the records from the input file that match the specified expression (LastName=Smith) according to the configuration specified in the configuration file.

Use case 6: Display help

Code:

ffe --help

Motivation:

This use case is helpful when you want to view the help documentation and usage information for the “ffe” command. It provides a quick reference for the available options and their purposes.

Example output:

The command will display the help documentation and usage information for the “ffe” command.

Conclusion:

The “ffe” command is a versatile tool for extracting fields from flat database files and transforming them into different formats. By utilizing configuration files and various command-line options, you can manipulate and manage data efficiently.