curl من الطرفية

Written Explanation

Is curl installed?

Many systems ship with curl. Check with:

curl --version

If you see a version number, you are ready. If not, install it with your system's package manager or from the official site (see References). The commands below assume a Unix-style shell such as Bash.

Windows note. In Windows PowerShell (the older, built-in version), curl is an alias for the Invoke-WebRequest cmdlet, according to Microsoft's documentation, so curl -i may not behave like the real tool. To run the real program there, type curl.exe. Newer PowerShell versions and Git Bash behave differently, so if a command seems to be rejected with strange parameter errors, try curl.exe. Quoting rules also differ between Command Prompt, PowerShell, and Bash; the examples here use Bash style.

The simplest form

curl "https://dummyjson.com/products/1?select=title,price"

With no options, curl sends a GET and prints the response body. Nothing else: no status, no headers. Fine for a quick look, risky when something goes wrong, which is why the next option matters.

When output goes to a file or pipe, curl may draw a progress meter. The option -s (silent) hides the progress meter and messages but still prints the data, as the manual explains. Add -S (or --show-error) with it if you still want to see errors. We use -s in this course to keep outputs clean.

-i: show the status and headers

The manual says -i (long form --show-headers in current versions, earlier --include) adds the response headers to the output. That means you see the status line first, then headers, then a blank line, then the body.

curl -s -i "https://dummyjson.com/products/1?select=title,price"

The real output began like this (we cut the long middle part of the headers and replaced it with ...):

HTTP/1.1 200 OK
Date: Wed, 04 Nov 2026 06:19:10 GMT
Content-Type: application/json; charset=utf-8
...

{"id":1,"title":"Essence Mascara Lash Princess","price":9.99}

This is the same information the Postman response pane displays: status, headers, body. Two relatives: -I (capital i) sends a HEAD request and prints only the headers, and -v (verbose) also shows the request that was sent.

Sometimes you only want the status code. The option -w (write-out) prints information about the finished transfer, and -o /dev/null throws away the body (on Windows cmd use NUL instead):

curl -s -o /dev/null -w "%{http_code}\n" "https://dummyjson.com/products/99999"

Real output: 404.

-H: add a header

-H "Name: value" adds a header. You can repeat it. The most common one for APIs is the Content-Type of a body you send:

-H "Content-Type: application/json"

-d: send a body

-d (--data) sends data as the request body. The manual says that for HTTP this uses the POST method, as a browser does when it submits a form, and it sends the data labeled application/x-www-form-urlencoded unless you say otherwise. For a JSON API that is usually not what you want, so combine -d with -H:

curl -s -i -X POST "https://dummyjson.com/products/add" \
  -H "Content-Type: application/json" \
  -d '{"title":"Dune"}'

The single quotes around the JSON stop the shell from touching the double quotes inside. The backslash at the end of a line continues the command on the next line (a Bash habit; in PowerShell the continuation character is a backtick, and in Command Prompt it is ^).

-X: choose the method

-X METHOD sets the method word. For PUT and DELETE you need it:

curl -s -X DELETE "https://dummyjson.com/products/1?select=title"

Remember the warning in the manual: -X only changes the word in the request line; it does not change how curl behaves otherwise. So -X POST together with -d is fine (it just repeats what -d already implies), but -X GET will not turn a -d body into a query string. And you do not need -X GET: GET is already the default.

Quote your URLs

In many shells, & means "run the previous command in the background" and ? or * may be treated as patterns. A URL such as https://dummyjson.com/products?limit=2&select=title,price contains &, so always put the URL in quotes:

curl -s "https://dummyjson.com/products?limit=2&select=title,price"

Without quotes, the shell cuts the command at &. The first part runs with only limit=2, and the rest is treated as a separate command. Use double quotes for URLs, single quotes for JSON.

Postman and curl side by side

Postman can even show you the curl equivalent of a request through its code-generation feature, and can import a pasted curl command (menu locations vary by version). That makes the two tools interchangeable.