To be fair, searching it in Google also gives TLDP pages as the top results. I think TLDP just has better SEO.
That's the danger behind PageRank. If something false is popular enough, it will replace fact.
Backlinks must come from other reputable (in google's algorithm's eye's) sites before they carry any weight.
So, this would mean, tldp.org has a lot of top-ranked linux/bash and related sites pointing to it's pages.