135 lines
4.0 KiB
Markdown
135 lines
4.0 KiB
Markdown
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# Json Data
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`jq` is your lightweight, flexible command-line JSON processor. It's built in portable C with zero runtime dependencies, making it simple to install and powerful for parsing JSON in Bash.
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-----
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### Demo Setup: QuizAPI
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This demo uses the [QuizAPI](https://quizapi.io/) to fetch JSON data. Obtain a free **API key** from their [client area](https://quizapi.io/clientarea/settings/token) to follow along.
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-----
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### Installing `jq`
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`jq` is easily installed via your system's package manager or direct download.
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* **Ubuntu/Debian:** `sudo apt-get install jq`
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* **Red Hat/Fedora:** `sudo dnf install jq`
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* **Arch Linux:** `sudo pacman -S jq`
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For other systems, refer to the [official `jq` download page](https://www.google.com/search?q=%5Bhttps://stedolan.github.io/jq/download/%5D\(https://stedolan.github.io/jq/download/\)). Verify your installation:
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```bash
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jq --version
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```
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-----
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### Basic JSON Parsing with `jq`
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Once `jq` is installed and you have your QuizAPI key, you can start processing JSON.
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First, set your API key:
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```bash
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API_KEY=YOUR_API_KEY_HERE # Replace with your actual key
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```
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Fetch questions using `curl`:
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```bash
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curl "https://quizapi.io/api/v1/questions?apiKey=${API_KEY}&limit=10"
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```
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The raw output is hard to read. Pipe it to `jq` for beautifully formatted and colored JSON:
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```bash
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curl "https://quizapi.io/api/v1/questions?apiKey=${API_KEY}&limit=10" | jq
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```
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This command makes the JSON output structured and easy to inspect.
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-----
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### Extracting Specific Elements
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To get only the first element from a JSON array, use `.[0]`:
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```bash
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curl "https://quizapi.io/api/v1/questions?apiKey=${API_KEY}&limit=10" | jq '.[0]'
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```
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This will output only the first JSON object in the array.
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-----
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### Fetching Key Values Across an Array
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To extract the value of a specific key (e.g., `question`) from every object in a JSON array, use `.[].key`:
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```bash
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curl "https://quizapi.io/api/v1/questions?apiKey=${API_KEY}&limit=10" | jq '.[].question'
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```
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This will return a list of all questions from the API response.
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-----
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### Integrating `jq` into a Bash Script
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Let's create a script to fetch a question and its answers, then display them. We'll use `jq` to parse specific fields and assign them to Bash variables.
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Create `quiz_script.sh`:
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```bash
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touch quiz_script.sh
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```
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Open `quiz_script.sh` and add (remember to replace `YOUR_API_KEY_HERE`):
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```bash
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#!/usr/bin/env bash
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# Your QuizAPI Key (replace YOUR_API_KEY_HERE with your actual key)
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API_KEY="YOUR_API_KEY_HERE"
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# Make an API call and get the first question object
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# Using -s for silent mode to suppress curl's progress meter
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QUIZ_DATA=$(curl -s "https://quizapi.io/api/v1/questions?apiKey=${API_KEY}&limit=1" 2>/dev/null)
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# Extract specific values using jq with raw output (-r) for Bash variables
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question=$(echo "${QUIZ_DATA}" | jq -r '.[0].question')
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answer_a=$(echo "${QUIZ_DATA}" | jq -r '.[0].answers.answer_a')
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answer_b=$(echo "${QUIZ_DATA}" | jq -r '.[0].answers.answer_b')
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answer_c=$(echo "${QUIZ_DATA}" | jq -r '.[0].answers.answer_c')
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answer_d=$(echo "${QUIZ_DATA}" | jq -r '.[0].answers.answer_d')
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# Output the question and answers
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echo "
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Question: ${question}
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A) ${answer_a}
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B) ${answer_b}
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C) ${answer_c}
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D) ${answer_d}
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"
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```
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Save, make executable, and run:
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```bash
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chmod +x quiz_script.sh
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./quiz_script.sh
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```
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The script will print a random question and its corresponding answers. For more advanced, interactive Bash quizzes, explore community projects that build upon these `jq` principles.
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-----
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### Conclusion
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`jq` empowers you to process **JSON** directly within your Bash terminal, facilitating seamless interaction with **REST APIs**. For deeper dives, consult the [official `jq` manual](https://www.google.com/search?q=%5Bhttps://stedolan.github.io/jq/manual/%5D\(https://stedolan.github.io/jq/manual/\)) and the [QuizAPI documentation](https://quizapi.io/docs/1.0/overview).
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> {notice} This content was inspired by a piece by softwareshinobi on Dev Team Six.
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