Curl PATCH Request With JSON Java Code An example of a Curl command for sending a PATCH request with JSON data to the REST API endpoint. In this HTTP PATCH request example, the Content-Type request header indicates the media type of the PATCH request. The JSON data is passed with the Curl -d command-line parameter.

Everyone has their preferred scripting language in which you are comfortable, others not so much, and this is especially true in the IT infrastructure space. I occasionally meet people who are proficient in many languages and these people tend to be programmers, annoying gits, or both (joking, it’s jealously really). Like many people who started out as windows admins I’m strong in PowerShell and I’ve learned how to work with REST APIs. But, what happens when you’re trying to use a modern REST API via swagger and the only example given is in cURL? In this post I’m going to give you 2 simple solutions to this problem.

The first solution is a bit of a cheat and isn’t reallyconverting it, but it is useful if you are running on Windows 10. You can simplyinstall the Windows Subsystem for Linux, load the disti of your choice (I usedUbuntu) then copy the cURL example direct into the terminal/shell:

One catch is that I see many cURL examples from REST APIs don’tgive you the full script needed to run the command. The curse of “presumedknowledge” in IT will catch you out. They think that you know exactly what elseis required to get the cURL command to work, but you’re a PowerShell user. Thisisn’t your bag. So, here’s an example from the Rubrik swagger UI:

This command is missing credentials for authentication and handling of an untrusted certificate (common in IT infrastructure). What you need is­­:

Thanks for contributing an answer to Stack Overflow! Please be sure to answer the question.Provide details and share your research! Asking for help, clarification,. Over the past two or three years, I have noticed that I have a 4X4 patch of hair on the front left side of my head. At best it might wave a bit, but nothing more than that. What can I do to get that part of my hair to curl again and be somewhat uniformed with the rest of my 3c hair. As you can see in the PATCH RFC5789, the HTTP request is similar what curl sends (use -trace-ascii to get to see the full curl communication). You might want to change the Content-Type (using -header). The mentioned missing status parameter is probably referring to contents in the request-body. Create a Patch File using diff. To understand this, let us create a small C program named hello.c.

If you installed the Linux subsystem and followed my example you’ve now successfully run a cURL command in Windows. But I promised you conversion to PowerShell and so that’s what we will do next.

Curl Patch Method

I recommend using PowerShell 6+ as it natively handles untrusted certificates and TLS 1.2. For interacting with REST APIs the equivalent of cURL in PowerShell is Invoke-RestMethod. Using this, here’s the same cURL command converted:

Let’s breakdown what I did here with the help of a diagram:

To explain:

1. cURL natively converts credentials into a base64 string, in PowerShell you need to convert it with this command (this is the most complex difference) and embed the credentials in the header.
2. The cURL equivalent for interacting with REST APIs in PowerShell is Invoke-RestMethod.
3. With cURL the credentials are specified using -u which it in turns uses to construct the header, we already constructed the header in step 1 so we don’t need a credential flag in PowerShell.
4. The method (GET ,POST, PUT etc) is signified by -X in cURL, in PowerShell its -Method.
5. In cURL we are adding the content type to the header, in PowerShell we specify the content with -ContentType.
6. To bypass warning on insecure certificates on the URL we are working with use –insecure in cURL, in PowerShell 6.0 we use -SkipCertificateCheck.
7. In cURL we are just specifying the URL at the end of the command. In PowerShell you should specify it after -uri (Uniform Resource Identifier, this case the URL)
8. The endpoint in my example doesn’t require any data so we are specifying null with -d. We could remove this section from cURL and if we were to specify this in PowerShell it would be with -Body.

Next time anybody says PowerShell isn’t as simple as cURL for working with REST APIs you can now call them out. The only major difference is PowerShell needs a little help converting the credentials to base64, whereas its native in a shell script.

The final example I’ll give covers converting cURL to PowerShell 5.1. Admittedly this isn’t as pretty if the endpoint is using an untrusted certificate and requires TLS 1.2, both native to PowerShell 6.0+. Accommodating for both these scenarios here is the script and cURL command converted to PowerShell 5.1:

Let me know via the drift chat if you have any questions or need more examples. Happy scripting,

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Curl Query Param

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Currently, if you open a persistent connection to a backend server
using libcurl, the connection will be left open indefinitely. If the
server closes the connection due to inactivity, libcurl will only
notice this when you attempt to reuse the connection.

This behavior is documented in the curl issue tracker:
http://sourceforge.net/tracker/?func=detail&atid=100976&aid=1358860&group_id=976

The big issue with curl's behavior is that it wastes connection
resources. Sockets sit around (practically forever) in CLOSE_WAIT. If
(for example) you don't need to reuse said connection, but instead
want to open a different connection to a different server, the dead
connection will still stick around forever. If, as a result, you run
out of file handles, you won't be able to open any more connections.

Fortunately, it is relatively easy to patch Curl to close dead
connections. The attached patch closes dead connections whenever you
attempt to open a new connection.

This patch makes two changes:
1. After cleaning up a dead connection, 'continue' instead of
returning FALSE. This ensures that we clean up all dead connections,
rather than just cleaning up the first dead connection.
2. Move up the cleanup for dead connections so that it occurs for
all connections, rather than just the connections which have the same
preferences as our current new connection.

Thoughts?

Cheers,

David

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Curl Patch Request Body

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