@eitama

True. The search engines on many sites are not very functional. However, for anyone interested in Unix/Linux, there is one source of information overshadowing all others: The internet. Following from that, the proper use of a search engine like Google should tackle those onsite shortcomings. All the OP had to do was to type "sudo gainroot" (Yes, with the quote brackets) in a Google search bar and he would've gotten more results (About 69,000 results (0.31 seconds) ) back than he bargained for. If you like, you add another keyword, for instance "permanent" to limit results (About 1,300 results (0.21 seconds) ). It's as simple as that.

Now, OP gets all upset over semantics while he could've been answered as well with a genuine and by far not uncommon STFU/RTFM. (I do not promote that type of answering, b.t.w. )