cURL is a command line tool for doing all sorts of interesting and essential URL manipulations and data transfers. The original goal of the program was to transfer files programmatically via protocols such as http, ftp, gopher, sftp, ftps, scp, tftp, and many others, via a command line interface. The main benefit of using the command line interface is that you can use the program in your Windows batch file or Linux shell scripts to automate many URL related processes. In this post you will see some essential things you can do using cURL.
1. Reading URLs
Read a plain URL.
curl http://www.google.com
Read a secured URL.
curl https://www.secure-site.com
Get a web page and store it in a file. The following for example will store the index page retrieved to the file savedpage.html
curl -o savedpage.html http://www.example.com/
Get a HTTP Basic authenticated page
curl -u username:password http://www.example.com/
Sometimes a page may redirect to another resource. By default CURL will not follow page redirections. To make CURL follow redirections use the -L option.
curl -L http://www.example.com/
2. Reading URL’s with variable GET parameters
You can also download pages with a variable GET parameter. For e.g take the following url:
http://example.com/pages.php?pageNo=35
The variable here is the pageNo parameter. You can download all the pages by adding a regular expression like parameter in the CURL url as given below.
curl -o pages#1.html http://example.com/pages.php?pageNo=[1-12]
This will download all the pages from page no 1 to page no 12 and save it to a corresponding file.
3. Reading document information
Show document headers only
curl --head http://www.google.com/
You can also use it on any specific resource.
curl --head http://www.google.com/logo_plain.jpg
Dump document headers to a file
curl --dump-header headers.txt http://www.google.com/
4. CURL and FTP
Get a FTP directory listing
curl ftp://username:password@example.com
To get the listing of a different directory append the directory name to the URL.
curl ftp://username:password@example.com/directory/
Upload a file to a remote directory using FTP
curl -T uploadfilename -u username:password ftp://sitename.com/myfile
The ‘uploadfilename’ file will be copied to the remote site and named ‘myfile’. If the destination filename is eliminated the file will be copied with the original name. By default the file will be copied to the root directory. To copy to some other directory specify the directory after the site name;e.g.
curl -T uploadfilename -u username:password
ftp://sitename.com/directory/myfile
5. To POST to a page.
You can also process a POST request using CURL. The data will use the application/x-www-form-urlencoded encoding. Lets say you have the following POST form in your page:
You can use the following CURL command to POST the request.
curl -d "item=bottle&category=consumer&submit=ok"
www.example.com/process.php
6. Referer & User Agent
HTTP requests may include a ‘referer’ field, which is used to tell from which URL the client got to this particular page. Many programs/scripts check the referer field of requests to check the source of the request. You can simulate the referer field by the following command.
curl -e http://some_referring_site.com http://www.example.com/
All HTTP requests may set the User-Agent field. It names what user agent or client that is being used. Many web applications use this information to decide how to display web pages or use it to track browser usage. You can impersonate a particular browser by the following method:
curl -A "Mozilla/5.0 (compatible; MSIE 7.01; Windows NT 5.0)"
http://www.example.com
There are many more options you can use with curl, the ones given above are just some you may require on a regular basis.
Exactly what ive been looking for.. cheers dude..
Nice. Do you perhaps know how to use curl to simulate a cross-domain http request ?
I am trying to set my tomcat server to return Access-Control-Allow-Origin: * in the headers. I found something that says it does it but I want to confirm that the header is set.
great post, thanks a mil!
Thanks, I’m a totally nubie at Curl. Every other page I’ve looked at has too much details and confuses me. I’m now clear that some lines of code are there to simulate a real user on the destination website.
Hi,
Thanks for commands, after downloading cURL zip folder, in windows 7, where do I need to cd to in order to run/execute the commands?
Thanks
wow. thanks sir. interesting app with console.
getting familiar with linux system.
Very nicely explained. very Impressive. thanks very much!! 🙂
Exactly waht I was looking for… thanks!!! cheers.
Thanks. I didn’t know you could set the destination filename when uploading via FTP.
nice
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Is there a command in CURL to delete a file from FTP in windows ?
Hello!
my question is how to use curl if I want to get data directly from FTP server… suppose my application wants to get data from FTP server whenever FTP server tries to send data to FTP client. What I want is to fetch data before FTPServer sends it to TCP socket, then I want to add my own data(at the start of the payload), then send it to TCP.Is it even possible through CURL. I am using visual studio 2010. any suggestions will be appreciated. thanks in advance.
Was looking for a simple curl tutorial and found this one. Thanks Sameer