use strict;
use warnings;

my ($user, $third, @data);

$user = 'Thomas';
$third = 'newvalue';

chomp(@data = <DATA>);
for (@data) {
    # Skip if user is not $user
    next if !m/^\Q$user\E\s*:/;
    # Change third field and exit loop
    @_ = split /:/, $_;
    $_[2] = $third;
    $_ = join ':', @_;
    last;
}

# Print data back to file (replace this)
print $_, "\n" for @data;

__DATA__
Username   :  Password  :   Download |
Tom       :   12345678  :
Thomas     :  12345678   :  121312313123131313

[download]

In reply to Re: adding an element in existing file.. by TedPride
in thread adding an element in existing file.. by bran4ever

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.