How to Use the Command 'jtbl' (with Examples)

The jtbl command is a utility specifically designed to convert JSON and JSON Lines data into neatly formatted tables that can be displayed in the terminal. This utility aids developers, data analysts, and system administrators who routinely work with JSON data, providing them with the ability to easily view and interpret JSON structures without delving into complex manual formatting. By offering a variety of options for managing how data is displayed, jtbl allows for significant flexibility in presenting JSON data concisely and effectively within a terminal environment.

Use Case 1: Print a Table from JSON or JSON Lines Input

Code:

cat file.json | jtbl

Motivation:

When working with JSON or JSON Lines data, the data is often displayed in a nested format that can be cumbersome to read and understand directly within a terminal. By converting JSON files into a table format, you can quickly interpret data structures, data relationships, and individual data elements. Using the jtbl command without additional options allows for a quick and straightforward view of the JSON data in a neat tabular format, making it accessible and easier to navigate.

Explanation:

• cat: This command reads the contents of a file and outputs them to the terminal.
• file.json: This represents the JSON file you want to read.
• |: The pipe symbol passes the output of the cat command as input to the jtbl command.
• jtbl: This command processes the JSON input and displays it as a table in the terminal.

Example Output:

+---------+-------------+
|  Name   |    Age      |
+---------+-------------+
| John    |     30      |
| Mary    |     25      |
+---------+-------------+

Use Case 2: Print a Table and Specify the Column Width for Wrapping

Code:

cat file.json | jtbl --cols=width

Motivation:

JSON data can sometimes be extensive, with long strings that may make terminal output unwieldy. In such scenarios, specifying column width ensures that the output remains readable within the constraints of the terminal size. By wrapping text at a defined width, you maintain the readability and neatness of the table output within certain spatial limits.

Explanation:

• cat: Reads the contents of the JSON file.
• file.json: The JSON file whose contents are to be displayed.
• |: Passes the JSON data output to the jtbl command.
• jtbl --cols=width: This option sets the maximum width of each column, so longer text can be wrapped, maintaining the legibility of the table format.

Example Output:

+---------+------+
|  Name   | Age  |
+---------+------+
| John    |  30  |
| Mary    |  25  |
+---------+------+

Use Case 3: Print a Table and Truncate Rows Instead of Wrapping

Code:

cat file.json | jtbl -t

Motivation:

In situations where terminal width is constrained, and wrapping columns would disrupt the readability by causing rows to extend excessively vertically, it may be desirable to truncate the data at the column width instead. This option is beneficial when working with large datasets where expanded row size may become difficult to read or process due to screen constraints.

Explanation:

• cat: Outputs the contents of the file to the terminal.
• file.json: The input JSON file.
• |: Connects the cat output to jtbl.
• jtbl -t: The -t option directs the jtbl tool to truncate the rows in the table at the designated column width rather than wrapping.

Example Output:

+-----------+------+
|  Name     | Age  |
+-----------+------+
| John      |  30  |
| Mary      |  25  |
+-----------+------+

Use Case 4: Print a Table and Don’t Wrap or Truncate Rows

Code:

cat file.json | jtbl -n

Motivation:

For users who prefer to see the entire content of each data cell without any modification through wrapping or truncation, the -n option in jtbl provides a solution. It ensures that columns display the complete content as is without alteration, which might be critical when exact data representation is crucial—for example, when auditing logs or reviewing verbose data entries.

Explanation:

• cat: Displays the contents of the specified file.
• file.json: The JSON file being analyzed.
• |: Pipes the data to the jtbl program.
• jtbl -n: The -n option indicates that neither wrapping nor truncation should be applied, allowing data to flow freely based on its original size.

Example Output:

+---------+--------+
|  Name   | Age    |
+---------+--------+
| John    | 30     |
| Mary    | 25     |
+---------+--------+

Conclusion:

The jtbl command offers versatile options for viewing JSON data within the terminal, thereby easing the analysis and interpretation of such data. Whether you need to adjust wrapping styles or ensure precise data representation, jtbl provides functionalities that cater to various data presentation needs, making it an essential tool for professionals dealing with JSON and JSON Lines data files.