Do you know how to use cURL?

Downloading and installing cURL

cURL is available on many platforms, including Windows (all variants), OSX (all versions) and Linux (all distros). cURL is available from the cURL website at http://curl.haxx.se/.

To install cURL on Linux, you should first check for cURL binaries in your distributions package repository. For exact instructions on how to do this, refer to your distribution’s documentation. On Ubuntu and other Debian variants, you can install cURL by issuing the following command:

$ sudo apt-get install curl

If cURL is not available in your distribution’s package repository or you’re running another operating system, you can find the right cURL package by following the download wizard at http://curl.haxx.se/dlwiz/. Simply select the “curl executable” option, input information about your computer and operating system and it will direct you to the correct file download. Once downloaded, extract any files in the archive to an easily accessible file (for example, c:\cURL on Windows).

cURL is a command-line tool. This means it is run from the command prompt (in Windows) or terminal (in Linux or OSX) and its results are displayed in the terminal window. There is no graphical interface. So to use cURL, you first have to open a command-line window.

On Windows, go to Start -> Run and enter “cmd” (without quotes) into the dialog and press enter.

On OSX, open the Terminal application. You’ll find this in the Applications/Utilities folder.

On Linux, open a Bash Prompt or Terminal window. Again, since all distributions are different, refer to your distributions documentation for more detailed information. On Ubuntu, you can open a bash prompt by going to Applications -> Accessories -> Terminal.

Though Windows, OSX and Linux all run different command-line shells (the program that interprets commands on the terminal and runs executables), the commands presented here will work on all of them.

First, change the directory to where you extracted the cURL archive. If you installed cURL using an installer or a package on Linux, cURL will already be in your path (meaning it can be run even though you’re not in the same directory) so this isn’t needed. For example, if I placed cURL in C:\cURL on my Windows computer, I would issue the following command.

> cd c:\cURL

You can now issue cURL commands. On Linux or OSX, you may have to prepend ./ to your commands. For example, instead of curl http://some/url, the command you’d use would be ./curl http://some/url.

To test cURL, enter the following command:

curl -I http://twitter.com/

You should see HTTP response headers. The first line should be “HTTP/1.1 200 OK.” This means you’ve made a successful request to Twitter using cURL.

Using cURL

cURL is a command-line tool. This means it’s launched from a command line with a number of switches and parameters. Switches change how the cURL command will act, and begin with the – character. For example, the previous example used the -I switch, which means to display the HTTP response headers only, and not the HTTP response body. Parameters pass information to either a switch, or the cURL command itself. In the previous example, the Twitter URL was a parameter.

Please refer to the following URL for the various options available in cURL: http://curl.haxx.se/docs/manpage.html

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Posted by Satish Talim

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