mywibox[s].widgets = {
        {
        mycpuimg, myspace, mycpu,
        myspace, mysep, myspace,
        mymemimg, myspace, mymem.widget,
        myspace, mysep, myspace,
        myfsrootimg, myspace, myfsrootlbl, myspace, myfsroot.widget,

-- this part procure an error, can i use "if" there?
        if os.execute("df | awk '{ print $6 }' | grep /") == 0 then
        myfsrootimg, myspace, myfsrootlbl, myspace, myfsroot.widget,
        end

            layout = awful.widget.layout.horizontal.leftright
        },
        layout = awful.widget.layout.horizontal.rightleft
    }