Ah - thanks clarifying that he targets OSX people. I didn't think that dstat, xargs, curl, vim, screen, rsync, or ack were obscure; but it makes sense if it the audience is OSX users.
I don't think OSX is specifically that important - I've met plenty of "new" linux users who have no idea htese tools exist either - linux has a gui too, you know.
Converseley, there are plenty of long-term unix experts out there who also find that a mac makes a nice workstation that still satisifies their need for unix tools plus other stuff.
Not a dig at OSX users. I have a macbook in addition to a thinkpad running a less common distro in front of me right now. I'm thinking of it in a Bayesian way: if a person is a Linux user or an OSX user, I expect them to know all/most of those tools. However, given that a person (limited to Linux or OSX users) doesn't know about those tools, I expect them to be an OSX user.
There really is no "target" audience of this post. :) It just started out as a list of "recommended" tools, then people started suggesting stuff -- some of which I knew, some of which I don't, some of which run on every unix, some only on Linux.
And it was easiest to take the screenshots from my OS X laptop. For some tools, like powertop, I had SSH-d into various Linux or FreeBSD boxes.
Some of these are uncommon enough that they are not ported to every package manager system, too. :(
Edit: looking at the site again, at least one of those screenshots is from OS X. htop lists /sbin/launchd and several processes from /Library/Frameworks.
