Below is my code.

#!/usr/bin/perl

use strict;
use warnings FATAL => 'all';

my $pid = fork();
my $output;

if ($pid) {
    print "forking child.\n";
    $output = qx( lst 2>&1 );
}

waitpid ($pid, 0);
print $output;

__OUTPUT__
Use of uninitialized value in print at 2.pl line 15.
forking child.
Can't exec "lst": No such file or directory at 2.pl line 11.
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Questions:
1. Why am I getting the uninitialized value message? Line 15 is the print $output.
2. Why is the error showing up first? Shouldn't it "wait" until the child is finished before attempting to print the output?
3. If I remove 'use warnings...', then I will not see the uninitialized message. But print $output will not show me anything.