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Technical
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Thursday, 20 April 2006 14:48 |
Libcurl is a free and easy-to-use client-side URL transfer library
used often for getting files using URL syntax. Curl is an important
library for PHP softwares such as billing
softwares (eg: ModernBill ) which communicates with banks and payment gateways often.Libcurl helps to communicate with remote servers with ease.
In this article , we'll see how to install or upgrade libcurl to a
new version ( 7.15.3 ) and then integrate it to the PHP running in
the server. Following steps were successfully tested on a Plesk 7.5
server running on RHEL-3.
Libcurl is under GPL & it can be downloaded from http://curl.haxx.se
& installed freely.
- wget http://curl.haxx.se/download/curl-7.15.3.tar.gz
- tar -xzf curl-7.15.3.tar.gz
- cd curl-7.15.3
- ./configure
- make
- make install
By default curl is compiled with ssl support. If you've installed
openssl in a custom directory , make sure that you give the "-with-ssl="
option while compiling.
On successful compilation curl is installed to /usr/local/ directory.
Accessing secure sites ( https ) through curl requires a list of certifying
authorities to be available for curl.
There are many a ways to get the latest ca-bundle , and the curl developers
themselves provide one at
http://curl.haxx.se/ca/cacert.pem
By default curl looks for the ca bundle at /usr/local/share/curl/curl-ca-bundle.crt
. RPM installation of curl looks at /usr/share/ssl/certs/ca-bundle.crt
. You can verify the correct path by using the following command.
$curl-config -ca
To install the latest ca-bundle , follow these steps.
- $ wget http://curl.haxx.se/ca/cacert.pem
- $ mv /usr/local/share/curl/curl-ca-bundle.crt /usr/local/share/curl/curl-ca-bundle.crt.old
- $ mv cacert.pem /usr/local/share/curl/curl-ca-bundle.crt
To test the curl binary , give a URL as its argument and see the output.
Along with the webpage which it downloads , curl binary also gives
a statistics of data transfer . A sample output is as shown below.
$ curl http://www.yahoo.com > test.txt
| % |
Total |
% |
Received |
% |
Xferd |
Average Dload |
Speed Upload |
Time Total |
Time Spent |
Time left |
Current Speed |
| 100 |
32420 |
0 |
32420 |
0 |
0 |
14676 |
0 |
-:-:- |
0:00:02 |
-:-:- |
41571 |
To integrate with php ( which is assumed to be already working in
the server ), perform the following steps
- Download the php sourcecode from http://php.net
- Untar and cd php-X.X.X
- In your configure command , add "-with-curl=/usr/local''.
Php looks for the include/curl/ inside the directory we give here,
when configuring.
( tip: To make sure that existing configuration is not lost, get the
configure command from phpinfo() )
- make && make install.
- restart apache.
Done !!!
To test if php with curl is working correctly , you can the test script
given at http://php.net/curl .
$ch = curl_init("http://www.example.com/");
$fp = fopen("example_homepage.txt",
"w");
curl_setopt($ch, CURLOPT_FILE, $fp);
curl_setopt($ch, CURLOPT_HEADER, 0);
curl_exec($ch); curl_close($ch); fclose($fp);
?>
Change the url to one using secure connection to make sure that SSL
sites are also working as expected.
Sojish Krishnan
2006-04-21
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