;
close(FILE);
$sizefile = @file;
#reopen our guestbook file, and get ready to write to it
open(FILE, ">$guestbook") || die "I can't!\n";
#loop through our file, and imcrement the number of lines.
for($a=0; $a<=$sizefile; $sizefile++) {
#put the contents of our file into $_ just in case we don't #find
our comment below
$_ = $file[$a];
#Now, look through to find our comment, and if we do, print #our
new entry
if(//) {
print FILE "\n";
print FILE "$FORM{'usrname'}
\n":
if ($FORM{'city'} ) {
print FILE "$FORM{'city'}";
}
if ($FORM{'state'} ) {
print FILE "$FORM{'state'}\n";
}
if ($FORM{'url'} ) {
print FILE "$FORM{'url'}\n";
}
print FILE "$FORM{'comments'}
\n";
} else {
print $_;
}
}
close(FILE);
Sub Routines
Okay, we're almost home! This is starting to look like a serious
program!
The last thing we have to do is, define our sub routines:
&missing_name, &missing_email, &missing_comments ¬ify, &thanks. So,
lets do it.
Usually its considered good coding to comment where your sub routines
begin. I usually just do this:
############
# Sub routines #
############
Okay, you'll remember from our first lesson that when we actually
define a sub routine, we use the following format:
sub name_of_routine {
block of code
}
The "sub" tells Perl that this is a sub routine, and that the
"name_of_routine" is what we indentified with the ampersand
(&missing_name). We are going to make use of HTML's hidden form
variables. If the user forgets to enter their name, they will be
returned with a form that will ask for their name. The rest of the
information they filled in, in the first form is entered in hidden
form fields, that will then be passed to the script once all of the
required form fields are filled in.
Lets do our error message routines first:
sub missing_name {
print "Content-type: text/html\n\n";
print "You didn't enter your
name!\n";
print "\n";
print "You did not enter your name.
\n";
print " Please enter your name in the space provided below
\n";
print "\n";
exit;
}
There are a couple of very important things to consider when returning
forms to a user. One is to always escape (using the back slash) each
double quote, and to make sure that you use the exact same names in
your hidden form fields. If not, then the input will just be lost.
Also, with an error routine such as this, we always kill the rest of
the script with the "exit" command. If we didn't add this, then sure,
the user would get this message, but the rest of the script would
still run, and we would have a serious mess on our hands! So, all we
need are 2 more routines just like this, but ask for the missing
e-mail or missing comments.
Just a quick note. If they forget 2 or all 3 required fields, that's
okay. Perl will just return the error message for each missing field.
And once all of them have been satisfied, the program will continue.
Lets just bang out the other two error sub routines:
sub missing_email {
print "Content-type: text/html\n\n";
print "You didn't enter your
e-mail!\n";
print "\n";
print "You did not enter your e-mail address
\n";
print " Please enter your it in the space provided below
\n";
print "\n";
exit;
}
sub missing_comments {
print "Content-type: text/html\n\n";
print "You didn't enter any
comments\n";
print "\n";
print "You did not enter any comments
\n";
print " Please enter some comments in the space below
\n";
print "\n";
exit;
}
Okay, now that we've gotten that out of the way, now we just have to
define our other two sub routines, &thanks and ¬ify. If you
remember, these are the two sub routines that send an e-mail to the
user thanking them, and to you notifying you of a new entry,
respectively. So, if we're going to send an e-mail we have to tell
Perl that we are going to open a process (the e-mail program) You'll
remember that we did this in our first lesson. We use Perl's "open"
function, and create a filehandle so that we can "pipe" our output to
our sendmail program. We use Perl's pipe " | " to send data to another
process (or program). We can' t just print the output. Lets do this:
open(MAIL, "| $mailprog -t") || die "I can't open sendmail\n";
Now that we set up our filehandle and our pipe (remember we defined
$mailprog as the path to sendmail) we can get on with the business of
giving sendmail our output. Remember though, that this is a
subroutine, and as such, we must write it as the above error routines:
sub notify {
open(MAIL, "| $mailprog -t) || die "I can't open sendmail\n";
print MAIL "To: My Name \n";
print MAIL "From: Guestbook@myhost.com\n";
print MAIL "Subject: $FORM{'usrname'} added a new entry to your
guestbook\n";
print MAIL "$FORM{'usrname'} added a new entry to your guestbook\n";
print MAIL "$guestbook_url\n";
close(MAIL);
}
sub thanks {
open(MAIL, "| $mailprog -t) || die "I can't open sendmail\n";
print MAIL "To: $FORM{'usrname'} <$FORM{'email'}>\n";
print MAIL "From: Your Name\n";
print MAIL "Subject: Thanks!!!\n";
print MAIL "Thanks $FORM{'usrname'} for adding your entry to my
guestbook!\n";
print MAIL "I hope you'll stop by sometime again! $guestbook_url\n";
close(MAIL);
}
You'll notice that in the ¬ify sub routine the "To:" line is to
yourself, and in the &thanks sub routine, we want to send it to who
ever added the entry, so we make a reference to our assocative array.
When ever you want to use any piece of information the user entered,
all you have to do, once you create the associative array (as you did
in section "Associative Arrays") you can then use that information
by referencing the appropriate "keys".
Well, that's it! Lets review the final code. Check your code and make
sure you have something that looks like this:
#!/usr/bin/perl
# My Guestbook CGI program!
$guestbook =
"/home/your_name/public_html/guestbook/guestbook.html";
$guestbook_url =
"http://www.yourhost.com/~yourname/guestbook/guestbook.html";
$guest_cgi_url = "http://www.yourhost.com/cgi-bin/guestbook.cgi";
$notify = "yes"; #or set to "no"
$thanks = "yes"; #or set to "no"
$mailprog = '/usr/sbin/sendmail';
#Get our form input
read(STDIN, $input, $ENV{'CONTENT_LENGTH'});
#split our input and create our array @pairs
@pairs = split(/&/, $input);
#loop through @pairs and place the data in $name and $value
foreach $pair (@pairs) {
($name, $value) = split(/=/, $pair);
#translate all "+" into white space and decode hex stuff
$name =~ tr/+/ /;
$name =~ s/%([a-fA-F0-9][a-fA-F0-9])/pack("C", hex($1))/eg;
$value =~ tr/+/ /;
$value =~ s/%([a-fA-F0-9][a-fA-F0-9])/pack("C", hex($1))/eg;
#Create our associative array
$FORM{$name} = $value;
}
#Lets do some error checking. Make sure they filled out the
required fields
&missing_name unless $FORM{'usrname'};
&missing_email unless $FORM{'email'};
&missing_comments unless $FORM{'comments'};
#Now, lets check our options for sending e-mail
if ($notify eq "yes") {
¬ify;
}
if ($thanks eq "yes") {
&thanks;
}
#open our guestbook.html file
open(FILE, "$guestbook) || die "I can't open $guestbook\n";
#put the contents into @file
@file = ;
close(FILE);
$sizefile = @file;
#reopen our guestbook file, and get ready to write to it
open(FILE, ">$guestbook") || die "I can't!\n";
#loop through our file, and imcrement the number of lines.
for($a=0; $a<=$sizefile; $sizefile++) {
#put the contents of our file into $_ just in case we don't #find
our comment below
$_ = $file[$a];
#Now, look through to find our comment, and if we do, print #our
new entry
if(//) {
print FILE "\n";
print FILE "$FORM{'usrname'}
\n":
if ($FORM{'city'} ) {
print FILE "$FORM{'city'}";
}
if ($FORM{'state'} ) {
print FILE "$FORM{'state'}\n";
}
if ($FORM{'url'} ) {
print FILE "$FORM{'url'}\n";
}
print FILE "$FORM{'comments'}
\n";
} else {
print $_;
}
}
close(FILE);
################
# Sub routines #
################
sub missing_name {
print "Content-type: text/html\n\n";
print "You didn't enter your
name!\n";
print "\n";
print "You did not enter your name.
\n";
print " Please enter your name in the space provided
below
\n";
print "\n";
exit;
}
sub missing_email {
print "Content-type: text/html\n\n";
print "You didn't enter your
e-mail!\n";
print "\n";
print "You did not enter your e-mail address
\n";
print " Please enter your it in the space provided below
\n";
print "\n";
exit;
}
sub missing_comments {
print "Content-type: text/html\n\n";
print "You didn't enter
comments\n"; print "\n";
print "You did not enter any comments
\n";
print " Please enter some comments in the space below
\n";
print "\n";
exit;
}
sub notify {
open(MAIL, "| $mailprog -t) || die "I can't open sendmail\n";
print MAIL "To: My Name \n";
print MAIL "From: Guestbook@myhost.com\n";
print MAIL "Subject: $FORM{'usrname'} signed your guestbook\n";
print MAIL "$FORM{'usrname'} added a new entry to your
guestbook\n";
print MAIL "$guestbook_url\n";
close(MAIL);
}
sub thanks {
open(MAIL, "| $mailprog -t) || die "I can't open sendmail\n";
print MAIL "To: $FORM{'usrname'} <$FORM{'email'}>\n";
print MAIL "From: Your Name\n";
print MAIL "Subject: Thanks!!!\n";
print MAIL "Thanks $FORM{'usrname'} for signing my guestbook!\n";
print MAIL "I hope you'll stop by sometime again!
$guestbook_url\n";
close(MAIL);
}
Closing Thoughts
Wow! You made it to the end! Good job!!! Before I let you go and play,
let me just do a quick run down on the installation of this thing.
First, you'll need to HTML pages. One page should be your entry form
(using the same names as we discussed in "Error Checking and
Working with Output"). The other HTML page is your actual
guestbook.html file (the actual guestbook page) Remember, this
guestbook.html file is the one with the special comment.
Second, you'll need to create a directory in your place called
'guestbook' and chmod it to 777. This enables Perl to read, write and
execute anything that sits in this directory.
Third, place the guestbook.html file in this directory, and chmod it
to 777 as well.
Fourth, upload your newly created guestbook program to your cgi-bin,
and chmod it to 755. Also, you will of course need to change the
variables at the top of our code ($guestbook $guestbook_url and
$guestbook_cgi_url) all so they conform to your system. You'll also
want to check the location of sendmail and Perl itself. (Do this by
telnet'ing into your place, and type: 'which perl' and 'which
sendmail' This will tell you the location of each program)
You should be all set to go!
Okay, I'd like to close this by saying that, I showed you only ONE way
to do this. The motto of Perl is "there's more than one way to do
anything" So, having said that I urge you to take this code apart,
re-arrange things, experiement. Take what you have learned here and
apply it to different tasks. Pick up a couple of Perl books and learn
different things so that you can add on to existing code, like the one
I just walked you through. The learning doesn't stop just because you
know how to do one or two tricks. Actually, your learning is just
beginning. I have just begun myself. I learn new techniques and new
ways of doing things everyday. I am, not by a long shot, completed
with my Perl learning. There is so much more to do, writing a
guestbook is just a stepping stone. Now, stop reading my horrible
banter, and get out there and LEARN!!!
Tutorial written by: Dave Palmer
©199