my $first = $cgi->param('first_name'); my $last = $cgi->param('last_name'); my $file = $first . '_' . $last . '.csv'; open(DF,'<',$file);

First of all, note that this it is quite dangerous to use unfiltered user input to read a file. I would strongly recommend reading perlsec, enabling the -T taint switch, and filtering $first and $last for allowed characters.

The problem might be that you aren't checking your open for errors, as in open(DF,'<',$file) or die "$file: $!";. This would give you an error message that you can see in the server's logs, or for debugging (not production!) you can add use CGI::Carp qw/fatalsToBrowser/; to the top of the script. In general, see CGI Help Guide and Troubleshooting Perl CGI scripts.

Also, please use <code> tags to format any code, sample input, output, error messages, etc.

Update: I missed this because of the missing formatting at first, but you're trying to write the contents of the file (print $line;) before you output the headers (print "Content-type:text/html\n\n";). You need to print any headers before the contents of the page, and since you're already using CGI.pm, you should use its header function instead of writing the headers manually. Also, while ( my $line = <DF> ) is generally better than foreach my $line(<DF>) because the latter reads the entire file into memory before looping over the lines. And using a lexical filehandle (open my $fh, ...) instead of DF would be better too.

And the OP probably cargo culted got that from some old tutorial which should have been forgotten years ago. And somehow it's always often noobies that appear here with crusty code like this. Is there too much bad information out there or is the good one too hard to find?


holli

You can lead your users to water, but alas, you cannot drown them.

I feel that part of it relates to the popularity and ranking a lot of legacy content has, and the (often dubious) availability of old books. For people making minimum effort it's too easy just to cut and paste something old, which 'works', for various definitions of the term. Try phrasing some "How do I .... in perl?" type questions and check out the results.

coolsaurabh:

Please edit your post and wrap your code in code tags (<code> your code
goes here </code>) to get:

your code
goes here
[download]

Now on to your question: The biggest problem I see in your code is that you're not bothering to check the results of the open call. I suggest you do something like:

    open my $DF, '<', $file;
    if (! defined $DF) {
        print "Cannot open file '$file' because: $!";
    }
    else {
        while (my line = <$DF>) {
            print $line;
        }
        close $DF;
    }
[download]

This way, you can get an error message that may provide you some hints as to what the actual problem is.

I suspect that:

• you're not specifying the correct path to the file,
• there may be permissions issues with the file and/or path, or
• the file doesn't exist.

...roboticus

When your only tool is a hammer, all problems look like your thumb.

Hi,

You probably shouldn't allow arbitrary filenames, see WashFilename, use taint and launder dirty data ( WashFilename )

Also, obligatory, the checklists :) Basic debugging checklist , brian's Guide to Solving Any Perl Problem, CGI Help Guide , Troubleshooting Perl CGI scripts

cgi101 cgi102, more subs (more subs , cgi101)

You should print Headers before any other operation - this allows you to report error messages if necessary.

Remember that the $file location is relative to the web root.

Error check your file open, and report accordingly.

print "Content-type:text/html\n\n"; # Or $cgi->header...

open(my $DF,'<',$file) or print $cgi->h1("Error opening $file:$!");

while (defined (my $line = <$DF>))
{
        print $line, $cgi->br();
}
close $DF;
[download]

Update: I just noticed this is a dup of 11102294. Please reap main node and all replies including this one.

2019-07-28 Athanasius reparented

Please add  <code> ... </code> tags to make your post readable. Please see Writeup Formatting Tips, Markup in the Monastery, How do I post a question effectively? and How do I change/delete my post?

2019-07-28 Athanasius reparented