How to Write CGI Scripts With Perl

You'll probably want to utilize the web's common gateway interface, or CGI, to make the process go as smoothly as possible if you're looking to write your own scripts for the WWW. One of the languages CGI uses is called Perl, and Perl has become the standard in the software industry for writing CGI scripts, although CGIs can technically be written in any computer language.

Difficulty:

Moderately Challenging

Instructions

1. Configure the web server to allow the user to execute CGI scripts. The web server is configured to allow CGI scripts to run out of the cgi-bin directory for security reasons. If there is any doubt, ask the system administrator for that server.

2. Invoke Perl at the top of your CGI script. This line is called the 'shebang' line. On most servers, Perl's location is /usr/bin/perl. Accordingly, the shebang line should say #!/usr/bin/perl -wT. The -w option turns on additional debugging information. The -T option turns on taint mode which deters Internet hackers.

3. Write a small CGI script to test that the web server is configured correctly. It's a good idea to write a small script just to test that everything is configured before moving into a more challenging script. Write a simple CGI script to print "Hello World." Use print statements in Perl to accomplish this. For Example: print("Content-type: text/plain\n\n");
   print("Hello World.\n");

4. Verify that this CGI script works correctly on your web server. It's working correctly if you see 'Hello World' printed to the screen upon execution. If you see Perl source code, then troubleshoot your web server configuration.