#!/usr/local/bin/perl -w

use strict;
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open(FH, "<file.txt") or die "Could not open file.txt: $!\n";
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As suspected my the author of the article, this was lifted from a web tutorial. Not stolen, it was, after all, a tutorial... yet still.

It looks pretty convenient, at least from what I can see in mla's example. I am both impressed and intimidated that some portion of it is apparently user-editable.

#!/usr/bin/perl -w

# -w to turn on warnings

# XXX These should be fully qualified paths
our $DATA_FILE = 'character.data';
our $FORM      = 'save.htm';

use strict; # you should almost always use this
use IO::File;
use CGI qw/ -debug /;

# parse the user's submission
my $q = CGI->new;

# fetch previously stored data
my $fh = IO::File->new($DATA_FILE) or die "unable to read '$DATA_FILE'
+: $!";
my $disk = CGI->new($fh);

# overwrite values
foreach my $key ($q->param) {
  $disk->param($key, $q->param($key));
}

# XXX What happens when two users run this script simultaneously?
# Answer: data corruption. We need locking.
$fh = IO::File->new("> $DATA_FILE") or die "unable to write '$DATA_FIL
+E': $!";
$disk->save($fh);

# XXX Better to move the common code into a module.
# How do we know if system() worked?  See $? in perlvar
# This should be fully qualified too.
#system 'menu.cgi'             ;

my $out = join "\n", map { "$_=" . $disk->param($_) } $disk->param;

$fh = IO::File->new($FORM) or die "unable to read '$FORM': $!";
print $q->header, <$fh>, $out;
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This is a stunning amount of work just to help out a newbie.

Thanks! Of course I still don't understand half of what you have in here (grin). This is cool though, most of the examples I've found on the web so far are either too simple to be very useful, or insufficiently explained/commented and I can't tell what they are supposed to do.

What does this (use IO::File) do? It looks like you are instantiating an object, but I can't find a reference for the 'use' command. I've been using this language reference.

Any suggestions for a better online reference?

The perlfunc section of docs in your development environment is probably most convenient. In ActiveState those are distributed in a winhelp format and accessable through the AS start menu. On unix just type 'perldoc -f use'. use is like #include in C, but with specific behavior at compile time, and with regard to multiple inclusion.

1. perldoc perlfunc
2. perldoc perlsyn
3. perldoc perlop
4. perldoc IO::File

After Compline,
Zaxo

The reference you're using is for Perl 4, so it's obsolete. Take a look at www.perldoc.org.

I'd suggest you install Perl locally if you haven't already. It comes with a wealth of documentation that is very easy to use. For example, if you want to find out what use does you can simply run perldoc -f use.

The use IO::File just loads the IO::File module. And then, yes, I'm instantiating it. I just wanted to show you that there's an OO interface available for file operations. And again, if you have Perl installed, you should be able to just type perldoc IO::File to read about it.

The others are answering the code questions but I would offer reading suggestions.

Perl is a fun language but with any language there is a certain way of doing things. Your code shows that you are a Microsoft coder and that will get a few of the Perl elite types gnashing their teeth ;-)

If you seriously want to learn Perl I would suggest a few books

Beginning Perl by Simon Cozens. Very good coverage of Perl at a beginning level.

The O'Reilly Llama book "Learning Perl" is also a good place to start.

Writing CGI Applications with Perl by Kevin Meltzer

Finally if you want to play with Win32. Win32 Perl Programming by Dave Roth!

Good Luck

I have been in the (lucrative) wilderness of windows for a few years but my origins are c/c++/unix. I just like whitespace.

And I get enough win32 at work (grin)

Thanks for the tips. I am used to being able to pick up a new language or feature set by walking through a simple example. Apparently my c is too rusty to help me much - I may need to work a little harder for perl than is usually the case.

*laugh* Enjoy the rush of learning my friend, and when you do as I did - look up at the letter to a peer that you have "re-edited" to more clearly emphasize your thoughts and realize you have just written a Perl class module instead - you will know that the "bug" has you in it's grip.  At that point, give up all hope of enjoying any other language  - because their expressive capabilities are dwarfed by the endless nuances Perl so easily allows.  The ease of rapid deployment, prototyping and support that Perl (with CPAN) offers can not be matched by any other that I have seen (after 25 years of programming) and most importantly - there are people all around that speak it and <word usage=carefully>fanatically</word> support others learning it. - people like the fine Monks of the Abbey.

side note - when my "letter incident" happened, I had quite the blast then trying to explain why I thought it was so funny to my co-workers - only to be stared at with incomprehension.  At that point I realized, Perl is a different sort of language, and that all my C/C++ (and now C#) knowledge would only initiate the learning process for me, but was really not all that helpful at all.  Perl requires you to set aside a few preconceived notions about programming I think.



*G*

The solution? try chmoding the cgi script 777 and then run it. It might work then, as some server configurations give your perl script the same file access permissions as the permissions of the script you are running. Otherwise, either you (assuming you are the server administrator) or the server administration will have to set up the Web Server up differently.

For the problem of system "main.cgi"; not working, use system "perl main.cgi"; instead, since main.cgi probably does not have execute permissions.

The solution? try chmoding the cgi script 777 and then run it.

Leaving the script at 0777 is very foolish. Do try this solution, but if it works, immediately re-set the file permissions to something harmless like 0744, and learn about unix permissions before you set it to something that works again.

The number 0777 may not mean a thing to you, so here's a small explanation: it allows everyone to run the file, read the file or change the file. When someone else changes the file, and you execute it, there might be disastrous results.

mt2k, please do never recommend 0777 as a mode for ANYTHING, as it's insecure. For executable scripts, 0755 should always be enough: that lets only yourself change it, but everyone can read or execute it.

U28geW91IGNhbiBhbGwgcm90MTMgY
W5kIHBhY2soKS4gQnV0IGRvIHlvdS
ByZWNvZ25pc2UgQmFzZTY0IHdoZW4
geW91IHNlZSBpdD8gIC0tIEp1ZXJk

Aha, there is a reason, however, why I suggested 0777 as the permission for scripts.
The server I am working on is setup in a bad way.
Whatever permissions are set for the script are the same permissions my scripts are granted for files.

If I chmod the script 0755, then my script can read and execute files, but it cannot write to files!!
If I chmod it to 0777 it can read, execute, and write to/from files.

This is a very strange behaviour, but it is how the server I am on works. So to be able to write to files, I HAVE to chmod my scripts to 0777.

It didn't occur to me that my ISP webserver may have settings that restrict what is available for public access. It should have, IIS certainly does.

Now I'm curious. I'll ask my ISP.

CGI Help Guide

cheers

tachyon

s&&rsenoyhcatreve&&&s&n.+t&"$'$`$\"$\&"&ee&&y&srve&&d&&print

I was in the middle of applying your suggestions when suddenly everything started working. I hate that, I mean I'm glad it's working but now I don't know why. Magic scares me.

I checked permissions, but all files involved had already been 777'd.

I added an 'or die' to one of file opens, and added 'perl' to the system call. I added the -w arg to the opening line and 'use strict'. But then the code wouldn't compile at all, it wanted some kind of package (?) for each global? I am clearly going to need more info here... I assumed 'my' meant a local scope and 'our' meant global. So much for the handy perl tutorial.

So I commented out the strict and removed the -w and checked to see if it would compile. And it not only did but also worked as well.

I do not understand at all why it suddenly worked when I made no changes to the pieces that seemed to be broken.

I have some more specific questions to specific replies, but first I wanted to thank all of you, very much, for helping me.