在Perl中将系统命令分配给阵列

Question

I'm attempting to assign the Linux system command top -n1 to an array and then eliminate the first seven lines of the text that is written to a text file. When I go to print elements from my array, I get an error saying use of uninitialized value. Can someone show what I'm doing wrong when assigning my array to the system command? Thank you.

Edit: I might also add, I'm looking to delete the first seven lines by using array slicing.

sub     processlist
{
     my $num_of_lines = 0;
    my @top_command = `top -bn1 >toptmp.txt`;

    #opening temp file, and output file.
    open(my $in, '<' , "toptmp.txt") or die "Can't read the file: $!"; #file used for initial reading
    open(my $out, '>', "top.txt") or die "can't write to file: $!"; 

    print $top_command[0], "\n";
    #looping deleting first 7 lines
    while(<$in>)
    {

            if($num_of_lines > 6) #starts writing to top.txt past line 7 (counting starts at 0)
            {
                    print $out $_;
            }
    $num_of_lines++;
    }
    close $out;
    close $in;
    system("rm toptmp.txt"); #erasing tmp file.

}

Answer 1

Use instead

top -bn1 | tail -n +8

No need to reinvent the wheel when the tail command will already do what you want

Answer 2

You are writing the top results to a file, if you want to get them to the variable you should not do that.

Use top -bn1 instead of top -bn1 >toptmp.txt