Your main problem is that you're checking ne

       if($name ne $user) {

[download]

so, unless every entry in the USERNAME file holds the name in question, this will match and quit with ERR.

Also, your way of reading the file 

    while(<USERNAME>)                     # reads first entry
        {
        my @newusername = <USERNAME>;     # reads remaining entries
    foreach $name (@newusername)
        ...

[download]

skips the first entry for the comparison...

Try something like this: 

...
my $found;
while (my $name = <USERNAME>) {
    if ($name eq $user) {
        $found = 1;
        last;
    }
}
unless ($found) {
    print $client_socket "ERR\n";
    ...
    exit;
}
print $client_socket "ACK\n";

[download]

And either chomp both $user and $name, or none.  As you have it, $name has a trailing \n, while $user hasn't.

In reply to Re^2: Accessing a file from the perl by Eliya
in thread Accessing a file from the perl by abcdefg

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