CGI : Make it work for public_html directory

Hello everyone,

In this post we will discuss the way in which we will tell the server that we will place our output files in a directory inside the home folder and that output files must run on the particular link.

So, let’s start the process. First of all we need a directory named public_html within which there should be a folder named cgi-bin in the home directory. The command for this process is,

mkdir -p ~/public_html/cgi-bin/

-p flag is used to create the directory no matter what and ~ sign represents the home directory.

Now as the folders are created we need to put some dummy file inside them and check out the results in the browser to make sure that everything is working properly. Go to the file.

$ cd ~/public_html/cgi-bin/

$ vim test.cpp

Now add this content to the file. Read this post if you want to know more about vim.

#include <iostream>
using namespace std;

int main ()
{

cout << “Content-type:text/html\r\n\r\n”;
cout << “<html>\n”;
cout << “<head>\n”;
cout << “<title>Lello World – First CGI Program</title>\n”;
cout << “</head>\n”;
cout << “<body>\n”;
cout << “<h2>Lello World! This is my first CGI program</h2>\n”;
cout << “</body>\n”;
cout << “</html>\n”;

return 0;
}

Save this file with the name test.cpp or with any other .cpp extension.

Now if you are following the BaKaPlan tutorial, you will be having G++ installed in your system but before compiling this file we need to complete some steps that are important to configure this public_html folder.

$ sudo a2enmod userdir

Which mean apache2 enable mod. If you want to look more into this matter you can open the manual by using this command.

$ man a2enmod

When a2enmod command is used two new files are added in the list in the directory modes-enabled. The opposite command is a2dismod which means apache2 disable mode. when using terminal type these commands.

$ cd /etc/apache2/mods-enabled

$ ls

You will see two files added to list at the end named userdir.conf and userdir.load. These files helps in the cofiguration of the public_html folder. Now you must restart apache2 by using this command.

$ sudo service apache2 restart

Now you need to give permissions to the public_html folder. Use this command to give read permissions to others.

$ chmod -R 755 ~/public_html
$ sudo a2enmod cgi

$ sudo a2enmod cgid

$ sudo service apache2 restart

$ cd ~/public_html/cgi-bin/

$ cd /etc/apache2
$ sudo service apache2 restart
$ sudo apt-get install libcgicc-dev
$ sudo vim httpd.conf

Add this content to this file.

ScriptAlias /cgi-bin/ /home/*/public_html/cgi-bin/
<Directory “/home/*/public_html/cgi-bin”>
AllowOverride None
Options +ExecCGI -MultiViews +SymLinksIfOwnerMatch
SetHandler cgi-script
Order allow,deny
Allow from all
</Directory>

Now restart apache again

$ sudo service apache2 restart

Now it’s time to compile the program. If you don’t give any output name than compiled data will be saved in a file named a.out but you can give a name using -o flag.

$ g++ test.cpp -o test.cgi

test.cgi is the name of output file.

Now in the browser type this link by replacing username with your username.

http://localhost/~USERNAME/cgi-bin/a.out

If the output file shows itself on the browser then it’s working. If not then you might have done something wrong. Follow the procedure again and solve the problem.

Still facing problem please comment below.

 

CGI : Make it work in the default directory

Hello everyone,

If we want to make CGI work, we first must know that why is it used.

To know about the prerequisites read this post. 

CGI stands for Common Gateway Interface. CGI help you to compiled program output through the browser window. If we don’t have any tool to show the output of the program on the browser then output file(obj file in the case of C program) will be downloaded. Also CGI is not only used in the case of C or C++ but it can be for many other languages.

Also before going further into the topic I want to discuss some more about how the apache2 server works. This server recognizes a directory as its default working directory and shows out any html page in this directory which have read permissions to others. As when working with the browser we are working as others. This command can be used to open up the folder that folder of the server. Just add a file

cd /var/www/apache2/html/

Now if we want to show the output of the file on the browser through localhost then we must put the output file here or we must tell that the files in the next other directory must be treated as such to show the result in the browser.

So the procedure for this is explained on two of my friend’s blogs. Please check these both procedures as both of them show different ways in which CGI can be configured in the default directory.

https://amisha2016.wordpress.com/2016/02/18/task-2/

https://iamjagjeetubhi.wordpress.com/2016/06/03/cgi-in-c/

There might be some mistakes in both of the posts. If you find any, then you must comment it in the there respected blogs.

Still need help please comment below.