Down the 'ls' Rabbit Hole

Down the 'ls' Rabbit Hole(sysadvent.blogspot.com)

169 points by mgorsuch 15 years ago | 12 comments

jeffbarr 15 years ago |

These "down the hole" investigations can sometimes be used as the basis for open-ended interview questions.

I always ask candidates to tell me everything that happens between the time that they see an interesting link on the screen, click on it, and see the result. I've had great answers in the space of 2 minutes, and amazing ones that covered 15 or more. Some of the more spectacular answers referenced neurons, muscles, round-robin DNS, firewalls, load balancers, application servers, and more. I can really determine if they know how the web works or not.

jgershen 15 years ago |

Nice article; it reminds me of taking OS at CMU. There's something incredible about learning what happens all the way down when you call, say, printf. Suddenly the computer transforms from an incomprehensible black box into an fascinating marvel of engineering - but unlike a magician's act, the magic only gets better when you see how it works.

bhrgunatha 15 years ago | |

Aside from the interesting information about what is happening is the instructions on what tools to use to get the job done. An article like has a double payload; I wish more were like that.

jwatzman 15 years ago | |

I just finished that course this semester, and I totally agree. Really, I think that's what most of my upper-level undergrad CS classes have been -- taking something which is a huge, magical black box and pulling it apart to the point where I can (and do) build one myself.

birken 15 years ago |

It is worth noting this whole series is incredible. I used to work with the guy who started it (@jordansissel), and he was an incredible sysadmin/software engineer. If you go through the archives on the right side, you will find lots more incredible posts (although he doesn't write them all anymore, they are all of excellent quality).

silentbicycle 15 years ago | |

Seconded! It goes back two years, and hopefully will continue for many more. Excellent series.

brown9-2 15 years ago | |

Agreed, all of these articles are really well-written.

ihodes 15 years ago |

Note, for those following along, that Mac users can use dtruss (which is a shell script that makes DTrace easier to use and more like strace).

What a neat article! Makes me want to explore some other commands and write something similar up.

scrame 15 years ago |

Wow. Really informative.

I have used strace to try to debug unpredictable or unresponsive programs, but it never occured to me to just run it against the commands I rely on that actually work.

I did a combination gasp/chuckle when I saw the 'write(l, "bar\n" ...' at the end of the ls dump. There is something both humbling and obvious about seeing under the hood of the platform that I just take for granted.

azar1 15 years ago |

Heh, this is great. I just had to write a simple shell for my CS class, so going into more depth with some of the stuff in this article is great.

T_S_ 15 years ago |

Yes. I have this command aliased as 'fu'. Surprisingly easy to remember.

monos 15 years ago |

THE AMULET OF YENDOR: INSIDE THE KERNEL

JUST ONE MORE TURN...

http://en.wikipedia.org/wiki/NetHack