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Comment by Xdes | Hacker News Reader

Still doesn't tell me what dtrace does.

Read this: http://blog.bignerdranch.com/1907-hooked-on-dtrace-part-1/

Or you could just give a concise definition:

    >What is this "DTrace" thing? It stands for "Dynamic Tracing",
    >a way you can attach "probes" to a running system
    >and peek inside as to what it is doing.

It was my mistake to link you to a tutorial on the thing you are asking about. I don't know what came over me.

It's like awk, except that you match entry/exit of syscalls, function calls, method invocations (in ObjC/Java), and give code to execute with access to arguments, return values, stack trace, etc.

It can be used to write tools like strace (see "dtruss" on OSX), iotop, topsyscall, etc.

On Mac OS X, the way to get an idea of what dtrace can do is "apropos dtrace". That shows you the dtrace scripts that the OS ships with.

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