update elpac function

config.fish

function elpac -d 'print old packages in .emacs.d/elpa/, with any command, it will clean old ones'
    set -l elpa_path ~/.emacs.d/elpa
    # ls contains color which will affect the $pkg string, * part means only directories
    for pkg in (command ls $elpa_path)
        if echo $pkg | grep -q '[0-9]' # check if pkg $contains version number, $status = 0
            set -l pkg_ver (echo $pkg | sed 's!.*-!!')
            set -l pkg_name (echo $pkg | sed 's/[0-9.]*$//g')

            set pkg_com (echo $pkg_name(echo $pkg_ver | cut -c1))
            if test (command ls $elpa_path | grep "^$pkg_com" | wc -l) -gt 1
                set first (command ls $elpa_path | grep "^$pkg_com" | head -1 | sed "s/$pkg_com//g")
                set second (command ls $elpa_path | grep "^$pkg_com" | sed -n "2p" | sed "s/$pkg_com//g")
                if echo $first$second | grep -q '[a-zA-Z]'
                    continue # files/dirs like let-alias-1.0.5 and let-alias-1.0.5.signed
                end
                # echo pkg: $pkg, first: $first, second:$second
                set first_num (echo $first | sed -e 's/\.//g') # get rid of . in version number
                set second_num (echo $second | sed -e 's/\.//g')
                if test $firstnum -le $secondnum
                    echo $pkg_com$first is le
                    echo $pkg_com$second
                    set old $first
                else
                    echo $pkg_com$first is gt
                    echo $pkg_com$second
                    set old $second
                end
                if not set -q $argv[1]
                    command rm -rf $elpa_path/$pkg_com$old
                    echo $elpa_path/$pkg_com$old is deleted!
                end
                echo
            end
        end
    end
end