CLI output formats (json, table, text) in AWS - Commands & Configuration

Introduction

When you use the AWS command line, you can choose how the results show up. This helps you read the information better or use it in other programs.

When you want to see AWS resource details in a simple list format for quick reading.

When you need to get AWS data in JSON to use it in scripts or programs.

When you prefer a clean table view to compare multiple resources side by side.

When you want to save AWS command output in a file for later use.

When you want to switch between formats depending on the task, like debugging or automation.

Commands

This command lists your S3 buckets and shows the output in JSON format, which is easy for programs to read.

Terminal

aws s3api list-buckets --output json

Expected Output

{"Buckets":[{"CreationDate":"2023-01-01T12:00:00.000Z","Name":"example-bucket"}]}

→

--output - Sets the format of the command output.

This command lists your S3 buckets and shows the output in a neat table format for easy reading.

Terminal

aws s3api list-buckets --output table

Expected Output

-------------------------

|        ListBuckets     |

+-----------------------+

|  CreationDate          |

|  2023-01-01T12:00:00Z |

|  Name                  |

|  example-bucket        |

+-----------------------+

→

--output - Sets the format of the command output.

This command lists your S3 buckets and shows the output in plain text format, which is simple and easy to read.

Terminal

aws s3api list-buckets --output text

Expected Output

BUCKETS	example-bucket	2023-01-01T12:00:00Z

→

--output - Sets the format of the command output.

Key Concept

If you remember nothing else from this pattern, remember: use the --output flag to choose how AWS CLI shows your data, making it easier to read or use.

Common Mistakes

Not using the --output flag and getting default output that is hard to read or parse.

The default output may not fit your needs for readability or automation.

Always specify --output json, table, or text depending on your goal.

Using JSON output but trying to read it directly without a tool or script.

JSON is structured for programs, not easy for humans to read raw.

Use JSON output when you plan to process the data with scripts or tools.

Summary

Use the --output flag to control how AWS CLI shows command results.

JSON output is best for automation and scripts.

Table and text outputs are easier for humans to read quickly.

Practice

1. What does the --output json option do when used with an AWS CLI command?

easy

A. It displays the output as a simple text list.

B. It saves the output directly to a file.

C. It shows the output in a table format for easy reading.

D. It formats the command output as structured JSON data.

Solution

1. Step 1: Understand the purpose of --output option

   The --output option controls how AWS CLI displays command results.

2. Step 2: Identify what 'json' output means

   Choosing json formats the output as structured JSON, which is machine-readable and easy to parse.

3. Final Answer:

   It formats the command output as structured JSON data. -> Option D

4. Quick Check:

   --output json = structured JSON output [OK]

Hint: JSON output is structured and good for programs [OK]

Common Mistakes:

• Confusing JSON with table or text output
• Thinking JSON saves output to a file automatically
• Assuming JSON is for human reading only

2. Which of the following is the correct syntax to display AWS CLI command output in a table format?

easy

A. aws ec2 describe-instances --output table

B. aws s3 ls --output text

C. aws iam list-users --format table

D. aws lambda list-functions --output json

Solution

1. Step 1: Identify the correct option for table output

   The AWS CLI uses --output table to format output as a table.

2. Step 2: Check each option's syntax

   aws ec2 describe-instances --output table uses --output table correctly. aws iam list-users --format table uses --format which is invalid. Options B and D use other formats.

3. Final Answer:

   aws ec2 describe-instances --output table -> Option A

4. Quick Check:

   Table output uses --output table [OK]

Hint: Use --output table for readable tables [OK]

Common Mistakes:

• Using --format instead of --output
• Confusing text and table output options
• Missing the --output flag entirely

3. Given the command aws s3api list-buckets --output text, what is the expected format of the output?

medium

A. A JSON object with bucket details.

B. Plain text with bucket names and details separated by tabs.

C. An XML formatted list of buckets.

D. A human-friendly table with borders.

Solution

1. Step 1: Understand the --output text format

   The text output format produces plain text with fields separated by tabs, suitable for scripts.

2. Step 2: Match output format to options

   Plain text with bucket names and details separated by tabs. describes plain text with tab-separated values, which matches --output text. JSON and XML are not text formats, and table includes borders.

3. Final Answer:

   Plain text with bucket names and details separated by tabs. -> Option B

4. Quick Check:

   --output text = tab-separated plain text [OK]

Hint: Text output is tab-separated plain text [OK]

Common Mistakes:

• Confusing text output with JSON or table
• Expecting borders or formatting in text output
• Assuming XML output is default

4. You run aws ec2 describe-instances --output tab but get an error. What is the likely cause?

medium

A. The AWS CLI version does not support output formatting.

B. The command requires additional parameters to run.

C. The correct output format is 'table', not 'tab'.

D. The 'tab' output format is deprecated and replaced by 'text'.

Solution

1. Step 1: Identify the valid output formats

   AWS CLI supports 'json', 'table', and 'text' as output formats. 'tab' is not valid.

2. Step 2: Analyze the error cause

   Using 'tab' instead of 'table' causes a syntax error because 'tab' is not recognized.

3. Final Answer:

   The correct output format is 'table', not 'tab'. -> Option C

4. Quick Check:

   Valid formats: json, table, text [OK]

Hint: Use 'table' not 'tab' for table output [OK]

Common Mistakes:

• Typing 'tab' instead of 'table'
• Assuming 'tab' is a valid alias
• Ignoring error messages about output format

5. You want to write a script that extracts only the bucket names from aws s3api list-buckets. Which output format should you choose to easily parse the bucket names in a shell script?

hard

A. Use --output text for simple tab-separated values.

B. Use --output table and extract names from the table.

C. Use --output json and parse with a JSON tool.

D. Use --output xml for structured parsing.

Solution

1. Step 1: Consider parsing ease in shell scripts

   Shell scripts handle plain text easily, especially tab-separated values.

2. Step 2: Match output format to parsing needs

   --output text produces simple tab-separated output, ideal for shell tools like cut or awk. JSON requires extra tools, table is formatted for humans, XML is unsupported.

3. Final Answer:

   Use --output text for simple tab-separated values. -> Option A

4. Quick Check:

   Text output is easiest for shell parsing [OK]

Hint: Text output is easiest for shell scripts [OK]

Common Mistakes:

• Choosing JSON without JSON parsing tools
• Trying to parse table output in scripts
• Assuming XML output is supported