HTTP requests with curl in scripts in Bash Scripting - Practice Problems & Coding Challenges

Challenge - 5 Problems

💻 Command Output

intermediate

What is the output of this curl command?

You run this command in a terminal to get the HTTP status code of a website:

curl -o /dev/null -s -w "%{http_code}" https://example.com

What will this command output?

Bash Scripting

curl -o /dev/null -s -w "%{http_code}" https://example.com

A The full HTML content of https://example.com

B 200

C An error message about missing output file

D Nothing (blank output)

💡 Hint

The flags -o /dev/null and -s hide the content and progress, -w "%{http_code}" prints the status code.

The command fetches the URL but discards the body (-o /dev/null), runs silently (-s), and prints only the HTTP status code (-w "%{http_code}"). For a successful request, it outputs 200.

💻 Command Output

intermediate

What does this curl command output?

This command sends a POST request with JSON data:

curl -X POST -H "Content-Type: application/json" -d '{"name":"Alice"}' https://httpbin.org/post

What kind of output will you get?

Bash Scripting

curl -X POST -H "Content-Type: application/json" -d '{"name":"Alice"}' https://httpbin.org/post

A No output, command runs silently

B The HTML page of httpbin.org homepage

C A JSON response showing the data sent and request details

D An error about unsupported HTTP method

💡 Hint

httpbin.org/post echoes back the POST data in JSON format.

The command sends JSON data to httpbin.org/post, which responds with JSON showing the data received and other request info.

🔧 Debug

advanced

Why does this curl command fail with a certificate error?

You run this command:

curl https://self-signed.badssl.com/

It fails with an SSL certificate error. Which option fixes this error by ignoring certificate validation?

Bash Scripting

curl https://self-signed.badssl.com/

A curl --insecure https://self-signed.badssl.com/

B curl --no-ssl https://self-signed.badssl.com/

C curl --ignore-certs https://self-signed.badssl.com/

D curl --skip-verify https://self-signed.badssl.com/

💡 Hint

The option to ignore SSL certificate errors is --insecure or -k.

The --insecure flag tells curl to skip SSL certificate verification, allowing connection to servers with self-signed or invalid certificates.

🚀 Application

advanced

How to save HTTP response headers to a file using curl?

You want to save only the HTTP response headers from a GET request to https://example.com into a file named headers.txt. Which command does this correctly?

A curl -D headers.txt https://example.com -o /dev/null

B curl -H headers.txt https://example.com

C curl -I https://example.com > headers.txt

D curl --headers https://example.com > headers.txt

💡 Hint

The -D option saves headers to a file; -o /dev/null discards the body.

Using -D headers.txt saves the response headers to the file. The -o /dev/null discards the body so only headers are saved.

🧠 Conceptual

expert

What is the effect of this curl command in a script?

Consider this bash script snippet:

response=$(curl -s -w "%{http_code}" -o response.txt https://example.com)

What will be stored in the variable response after running this command?

Bash Scripting

response=$(curl -s -w "%{http_code}" -o response.txt https://example.com)

A An empty string

B The full HTML content of https://example.com

C The path to the saved file response.txt

D The HTTP status code as a string, e.g., "200"

💡 Hint

The -w option outputs the status code to stdout, -o saves body to file, -s silences progress.

The command saves the response body to response.txt (-o response.txt), suppresses progress (-s), and outputs only the HTTP status code (-w "%{http_code}"). This output is captured in the variable response.