How do I handle errors in Curl?

Curl is a powerful tool used to interact with servers and APIs. It allows transferring data using various protocols and is widely used for testing, debugging and development purposes. However, like any other tool, things can go wrong and you may encounter errors while using Curl. This article will cover how to handle such errors.

Curl Errors

Curl errors can be handled in two ways: 1. By checking the HTTP status code. 2. By checking the Curl error code.

Checking HTTP Status Code

HTTP status codes can tell you if a request was successful or not. A status code of 2XX means the request was successful, 4XX means there was a client error, and 5XX means there was a server error.

Here's how you would check the HTTP status code in bash:

response=$(curl -s -o /dev/null -w "%{http_code}" http://example.com)
if [ "$response" -ge 200 ] && [ "$response" -lt 300 ]; then
    echo "The request was successful"
elif [ "$response" -ge 400 ] && [ "$response" -lt 500 ]; then
    echo "There was a client error: $response"
else
    echo "There was a server error: $response"
fi

In this example, the -s flag tells Curl to not output the progress meter, the -o /dev/null flag tells Curl to not output the content of the response, and the -w "%{http_code}" flag tells Curl to output the HTTP status code.

Checking Curl Error Code

Curl error codes are another way to determine if a request was successful. If a Curl request is unsuccessful, it will return an error code other than 0.

Here's how you would check the Curl error code in bash:

curl -s http://example.com
if [ $? -eq 0 ]; then
    echo "The request was successful"
else
    echo "There was an error: $?"
fi

In this example, the $? variable holds the exit status of the last command. If the exit status is 0, it means the command was successful. If the exit status is anything other than 0, it means there was an error.

Conclusion

Handling errors in Curl is important to ensure your scripts and applications work as expected. By checking the HTTP status code and the Curl error code, you can accurately determine if a request was successful or not.