hackerrank java challenge

https://www.hackerrank.com/contests/codewhiz-java-march-2016/challenges

Not much algorithm but a nice exercise on Java features.

interface Comparable {
  int compareTo(E o);
}

try {
} catch (Exception e) {
  throw e;  // rethrow
}

lambda expression

https://docs.oracle.com/javase/tutorial/java/javaOO/lambdaexpressions.html

num -> {
  for (int i = 2; i * i <= num; ++i) {
    if (num % i == 0) return false;
  }
  return true;
}

A nice OS book, Three Easy Pieces

http://pages.cs.wisc.edu/~remzi/OSTEP/

Disclaimer, I found this on Internet and know nothing about the author. This is a nice book that explains things quite well.

bash

http://mywiki.wooledge.org/BashSheet#Syntax

If you need to run several commands in background, do it like this:

./cmd1 args1 & ./cmd2 args2 & ./cmd3 args3

; is used to separate commands executed synchronously.

install mesos

Turns out to be much more work than expected.

I had to install a few packages manually because my ubuntu is too old, and apt-get cannot find anything.

libapr and its friends
svn headers
libcurl
and cyrus sasl

final command line is:
../configure LD_LIBRARY_PATH=/usr/local/lib SASL_PATH=/usr/local/lib/sasl2 --with-apr=/usr/local/apr --with-svn=/usr/local --with-curl=/usr/local --with-sasl=/usr/local

just typed make and it would take a while to finish.