Your code does not pass perl -c. That line with if shall be:

    if ($counter >= 1) {$message += $inline . "\n"};
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"my $counter = 0;
foreach my $inline (@ARGV)
    {
    if ($counter >= 1) $message += $inline . "\n";
    ++$counter; #a wasting, although not a big one ;-)
    }"
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Looks like the whole purpose of using $counter is to skip the first element, why not just:

for my $index (1 .. $#ARGV) {
    $message += $ARGV[$index] . "\n";
}
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Now why you skip the first element? Try this:

use strict;
use warnings;

for my $index (0 .. $#ARGV) {
    print $ARGV[$index] . "\n";
}
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Run it with perl -w blah.pl msg1 msg2 msg3, the output is:

msg1
msg2
msg3
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What are you try to skip ;-?