Your program does two things. It prints HTML output (a form you need to fill in) and then it appends to a data file. But you should only be appending to the data file after the form has been submitted. And your FORM tag has a very weird URL: "http://localhost/newuser.cgi?action=newuser?first?last" doesn't make a lot of sense. You probably just want "http://localhost/newuser.cgi".

Here is a simple program: 

#!/usr/bin/perl

use CGI;
use CGI::Carp qw( fatalsToBrowser );
use strict;
use warnings;

my $query = CGI->new;

# if we got here from a form being submitted,
# do the adduser() stuff
adduser($query) if $query->param;

print << "END_HTML";
<html>
<body>
<form method="post" action="thisprogram.cgi">
Username: <input type="text" name="user"><br>
First name: <input type="text" name="fname"><br>
Last name: <input type="text" name="lname"><br>
Password: <input type="password" name="pass"><br>
<input type="submit" value=" Add User ">
</form>
</body>
</html>
END_HTML


sub add_user {
  my ($q) = @_;
  open PASSWD, ">> $passwd_file"
    or die "can't append to $passwd_file: $!";
  print PASSWD join(":" =>
    $q->param('first'), $q->param('last'), $q->param('user'), $q->para
+m('pass')
  ), "\n";
  close PASSWD;
}

[download]
Jeff japhy Pinyan, P.L., P.M., P.O.D, X.S.: Perl, regex, and perl hacker
How can we ever be the sold short or the cheated, we who for every service have long ago been overpaid? ~~ Meister Eckhart

In reply to Re: Trouble getting CGI parameters by japhy
in thread Trouble getting CGI parameters by gitarwmn

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.