As was popular in the early days of the web, this assignment creates a simple guestbook. Unlike a physical guestbook, in this implementation the guest must sign the book before they can read it. Once they have signed, they can read every comment in the book. The purpose of this assignment was to learn how to write data to a text file using PERL.
This was an assignment from an introductory web programming course. It was written as quickly as possible to meet the minimum requirements of the assignment, and was not written using best practices. This is not a showcase of my best work. Instead, I am sharing it as a historical document of my student work.
This assignment is very basic. Security and design were not considered. Do not use this script in a public environment.
Directory Structure
This is directory structure for the files in this assignment.
The cgi-data directory is where the data file is stored. This is a special directory located outside the html directory for security purposes. If running the apache2 web server, the www-data user account requires read and write permissions to this directory in order to create, read, and write data files.
This data file, guestbook.txt, does not need to manually created. It will be created automatically the first time somebody signs the guestbook.
www
├─ cgi-data
│ └─ guestbook.txt
└─ html
├─ blog.html
└─ cgi-bin
└─ blog.pl
Source Code
This assignment includes 2 files.
blog.html
<html>
<head>
<title>My Guestbook</title>
</head>
<body>
<h1><center>My Guestbook</center></h1>
<p>
<form method=post action=cgi-bin/blog.pl>
<textarea cols=80 rows=10 name=note>
Enter your thoughts here...
</textarea>
<p>
<input type=submit name=submit>
<p>
</form>
</body>
</html>
cgi-bin/blog.pl
#!/usr/bin/perl
use CGI ':standard';
print header, start_html;
$note = param('note');
open (FD,">>../../../cgi-data/guestbook.txt") or die "Can't open guestbook file.";
print FD $note;
print FD "\n\n";
close(FD);
open(FD,"../../../cgi-data/guestbook.txt") or die "Can't open guestbook file.";
@notes = <FD>;
close(FD);
print "The following text is in the guestbook file:<br><br>";
foreach (@notes) {
print "$_<br>";
}
print "<br><a href=../blog.html>Back</a>";
print end_html;
Data file
The data file guestbook.txt will automatically be created the first time a guest signs the guestbook. This file contains every message left by a guest, separated by 2 line breaks. Each time a guest signs the guestbook, the script appends their message to the file, followed by 2 line breaks. The line breaks are important, because when displaying the contents of the guestbook, the script separates each message by a blank line.