How to use the command 'tbl' (with examples)

The tbl command is a powerful table preprocessor specifically designed for use with the groff (GNU Troff) document formatting system. It simplifies the creation and formatting of tables in documents that are later typeset by groff. Often used in technical and scientific publications, tbl allows users to produce complex tables that can be easily integrated into documents intended for eventual output to formats such as PostScript and PDF. Below, we’ll explore a couple of common use cases for this command, each highlighting different capabilities of tbl.

Use case 1: Process input with tables, saving the output for future typesetting with groff to PostScript

Code:

tbl path/to/input_file > path/to/output.roff

Motivation:

Imagine you’re tasked with preparing a document that includes several complex tables, and you need the final output in PostScript format. Perhaps you are preparing a set of academic papers for printing where high-quality typesetting is a requirement. tbl can preprocess your table data, making it ready for subsequent typesetting with groff, and ultimately leading to a high-quality PostScript document.

Explanation:

• tbl: This initiates the tbl command, invoking the table preprocessor.
• path/to/input_file: This represents the file path of your source document that contains tables you want to preprocess. The file must adhere to the formatting rules compatible with tbl.
• >: This character is used to direct the output of tbl to a new file rather than displaying it on the screen. This is useful for saving intermediate data in a workflow.
• path/to/output.roff: This specifies the file path where you want to save the processed output. The .roff extension indicates the file is now prepared for groff processing.

Example output:

Following execution, the path/to/output.roff file contains a reformatted version of your table data, ready for further processing by the groff typesetting system to produce high-quality PostScript documents.

Use case 2: Typeset input with tables to PDF using the [me] macro package

Code:

tbl -T pdf path/to/input.tbl | groff -me -T pdf > path/to/output.pdf

Motivation:

Suppose you are developing a technical manual or guide where the final format needs to be PDF, enabling easy sharing and uniform appearance across different devices and platforms. You need precise control over the document’s typography, especially if it includes formatted tables. This command allows you to achieve all of that by preprocessing your table file and directly converting it into a well-typeset PDF.

Explanation:

• tbl: As before, this command initializes the tbl preprocessor to handle table formats.
• -T pdf: This option tells tbl the target output format is PDF. It ensures that the preprocessing aligns with the requirements for later conversion into PDF.
• path/to/input.tbl: This is the path to your table source file.
• |: This pipe symbol allows the output from tbl to be directly fed into the next command without needing a temporary file.
• groff: This command invokes the groff typesetting system.
• -me: This option specifies the macro package to use. The [me] macro package is a set of macros from the troff typesetting system often used for formatting documents. It provides additional features and shortcuts for easier document control.
• -T pdf: This indicates that groff should produce output in PDF format.
• >: Directs the final output to a specified file.
• path/to/output.pdf: Specifies the destination file path for the output PDF document.

Example output:

Successfully running this command will create a path/to/output.pdf file. This file is a fully typeset PDF document that includes your formatted tables, ready for distribution or publication.

Conclusion:

The tbl command, when paired with groff, provides robust utilities for handling complex tables and generating high-quality document outputs such as PostScript and PDF. Understanding these use cases allows for greater flexibility in document preparation, ensuring pristine presentation of tables in technical and academic documentation. Whether your goal is print or digital distribution, tbl offers effective solutions to meet your formatting needs.