$ unzip k.zip
Archive:  k.zip
warning [k.zip]:  186 extra bytes at beginning or within zipfile
  (attempting to process anyway)
  inflating: from_ram.t


##</code><code>##

---------- 1 user user   7 2010-03-29 08:44 from_ram.t

##</code><code>##

$ file -ik k.zip
k.zip: application/zip; charset=binary


##</code><code>##

#!/usr/bin/perl
use strict;
use warnings;
use IO::Compress::Zip qw(zip $ZipError :constants) ;
use diagnostics;


my $zip;
zip './a.txt' => \$zip,
  name        => 'from_filename.t',
  AutoClose   => 1,
  BinModeIn   => 1
  or die "zip failed: $ZipError\n";

my $string = ss();

zip \$string => \$zip,
  name       => 'from_ram.t',
  ExtAttr    => '0666',
  Append     => 1 or die "zip failed: $ZipError\n";

open my $fh, '>','./k.zip' or die "$!";
print $fh $zip;

close($fh);

sub ss {
    return <<END;
a
b
c

END
}