Sometimes you want to explicitly show the logic used to deconstruct and reconstruct things:

$str = 'command1 command2 command3 "command4 --some-arg arg --some-oth
+er-arg 2" command5';
@words = split(/\s/, $str);
$arg_flag = 0;
for $i (0 .. $#words) {
    if ($words[$i] =~ /\"/) {
        if ($arg_flag == 0) { #starting a new command with args
            $arg_flag = 1;
            $words[$i] =~ s/\"//;
            $this_command = $words[$i];
        }
        else { #ending a new command with args
            $words[$i] =~ s/\"//;
            $this_command .= " ".$words[$i];
            push (@commands, $this_command);
            $arg_flag = 0;
        }
    }
    else {
        if ($arg_flag == 0) { #any old command
            push (@commands, $words[$i]);
        }
        else { # an arg in a command being built
            $this_command .= " ".$words[$i];
        }
    }
}
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It's clunky, but it works, and it preserves the logic for future generations to understsand.