Run a C Program on a Linux Server

Question

This question I\'m sure has been answered, I honestly don\'t know how to ask it via search though. So please excuse my lack of knowledge as this one of the only place I really h

Answer 1

One way is to run it as CGI, as @paddy already mentioned. However, the program will run slow, long startup time.

Another way is to run it using FastCGI. It will be much more faster, you just need a few modifications on your code to make it works, for example as CGI:

#include 
#include 

int main(int argc, char **argv)
{
    time_t timer;
    char time_str[25];
    struct tm* tm_info;

    time(&timer);
    tm_info = localtime(&timer);
    strftime(time_str, sizeof(time_str), "%Y/%m/%d %H:%M:%S", tm_info);

    /* Without this line, you will get 500 error */
    puts("Content-type: text/html\n");

    puts("");
    puts("");
    puts("  ");
    puts("");
    puts("");
    puts("   
Hello world!
");
    printf("   
%s
\n", time_str);
    puts("");
    puts("");

    return 0;
}

Compile it:

$ # 'cgi-bin' path may be different than yours
$ sudo gcc example.c -o /usr/lib/cgi-bin/example
$ wget -q -O - http://localhost/cgi-bin/example


  


   
Hello world!
   
2013/01/30 08:07:29


$ 

Using FastCGI:

#include 
#include 
#include 

int main(int argc, char **argv)
{
    time_t timer;
    char time_str[25];
    struct tm* tm_info;

    while(FCGI_Accept() >= 0)   {
        time(&timer);
        tm_info = localtime(&timer);
        strftime(time_str, sizeof(time_str), "%Y/%m/%d %H:%M:%S", tm_info);

        /* Without this line, you will get 500 error */
        puts("Content-type: text/html\n");

        puts("");
        puts("");
        puts("  ");
        puts("");
        puts("");
        puts("   
Hello world!
");
        printf("   
%s
\n", time_str);
        puts("");
        puts("");
    }

    return 0;
}

Compile it:

$ # Install the development fastcgi package, I'm running Debian
$ sudo apt-get install libfcgi-dev 
 ...
$ 
$ # Install Apache mod_fcgid (not mod_fastcgi)
$ sudo apt-get install libapache2-mod-fcgid
 ...
$ 
$ # Compile the fastcgi version with .fcgi extension
$ sudo gcc example.c -lfcgi -o /usr/lib/cgi-bin/example.fcgi
$ # Restart Apache
$ sudo /etc/init.d/apache2 restart
Restarting web server: apache2 ... waiting .
$
$ # You will notice how fast it is
$ wget -q -O - http://localhost/cgi-bin/example.fcgi


  


   
Hello world!
   
2013/01/30 08:15:23


$
$ # Our fastcgi script process
$ ps aux | grep \.fcgi
www-data  2552  0.0  0.1   1900   668 ?        S    08:15   0:00 /usr/lib/cgi-bin/example.fcgi
$ 

In poth programes, there is:

puts("Content-type: text/html\n");

This will prints:

Content-type: text/html[new line]
[new line]

Without it Apache will throw 500 server internal error.