while(<$fh>)

##</code><code>##

while(defined($_ = <$fh>))

##</code><code>##

    while(<$fh>){
        print;
    }

##</code><code>##

    local $_;
    while(<$fh>){
        print;
    }

##</code><code>##

    while(my $line = <$fh>){
        print $line;
    }