function clean_dir_by_file_num() {
    local err=0; local target=$1; local count=$2
    test $# -eq 2 || { show_error "Wrong usage of the function! Args=$@" "$FUNCNAME"; return 1; }
    total=`ls -l $target | grep '^-' | wc -l`
    to_delete=$[${total} - ${count}]
    test $to_delete -gt 0 && {
            for var in `ls -ltr $target | grep '^-' | head -n $to_delete | awk '{print $9}'`; do
                    test -f $target/$var || { show_error "File $target/$var doesn't exist or it's not a file!" "$FUNCNAME";}
                    show_notice "Deleting $target/$var ..." "$FUNCNAME"
                    rm -rf $target/$var 2>&1 || { show_error "Error on del $target/$var" "$FUNCNAME"; }
            done
    }

    return $err;
}

function clean_dir_by_dir_num() {
    local err=0; local target=$1; local count=$2
    test $# -eq 2 || { show_error "Wrong usage of the function! Args=$@" "$FUNCNAME"; return 1; }
    total=`ls -l $target | grep '^d' | wc -l`
    to_delete=$[${total} - ${count}]
    test $to_delete -gt 0 && {
            for var in `ls -ltr $target | grep '^d' | head -n $to_delete | awk '{print $9}'`; do
                    test -d $target/$var || { show_error "File $target/$var doesn't exist or it's not a file!" "$FUNCNAME";}
                    show_notice "Deleting $target/$var ..." "$FUNCNAME"
                    rm -rf $target/$var 2>&1 || { show_error "Error on del $target/$var" "$FUNCNAME"; }
            done
    }

    return $err;
}