Ask HN: Do we still need `-6` for `IP` command?

    ip -6 route del default

That does something different than

    ip route del default

I'm gonna answer myself, sometimes we do need to add `-6` for IPv6 situation, for example:

- `ip -6 r show`: If we don't add `-6`, we will just get the IPv4 route information. - `ip -6 r add`: If we don't add `-6`, when we add default route or something like that, we may miss IPv6.

So the answer is yes, we can use `ip` without `-6` when we do something for IPv6, but we still need it for specific situation.

it's the same reason I still have to type

   grep -i  pattern  filespec

Of course, grep should default to being case insensitive (-i), but it was a different world when it was written.