procedure main()
write(lcdsubstr(["/home/user1/tmp/coverage/test","/home/user1/tmp/covert/operator","/home/user1/tmp/coven/members"]))
end

procedure lcdsubstr(sL,d)   #: return the longest common sub-string of strings in the list sL delimited by d
local ss

/d := "/"
reverse(sL[1]) ? {
   if tab(find(d)+*d) || allmatch(ss := reverse(tab(0)),sL) then
      return ss
   }
end

procedure allmatch(s,L)   #: retrun s if it matches all strings in L
local x
every x := !L do
   if not match(s,x) then fail
return s
end