Taking screenshots with MacOSX is very useful when writting blogs or documents. The system has powerful built-in screenshot function. However, the default location to store the screenshot files is Desktop.

This blog will go through how to change the location of screenshots to another folder.

WebWorker has now been supported by majority of browsers (link). I have started to use WebWorkers seriously in my projects (web pages / web apps / cordova mobile apps).

Below reference pages were used while doing my study:

• Using webworkers
• webworker and phonegap

I found this tutorial is relatively simple to follow to create a simple PKI infrastructure

Run docker in docker

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docker run --privileged -i -t -d --restart=unless-stopped -p 2376:2376 -p 10000-11000:10000-11000 -p 10000-11000:10000-11000/udp -v /mnt/opt:/opt:rw -v /etc/docker:/etc/docker:ro -v /mnt/var/lib/docker:/var/lib/docker --name=docker docker:dind  -H tcp://0.0.0.0:2376 --storage-driver=aufs --tlsverify --tlscacert /etc/docker/ca.pem --tlscert /etc/docker/server.pem --tlskey /etc/docker/server-key.pem

Netcat (nc) is very powerful tool. Install apt-get install netcat
Send UDP packet with netcat:

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echo "content goes to server" | nc -u <ip> <port>

e.g.

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.select-type-1{
  -webkit-appearance: none;
  -moz-appearance: none;
  appearance: none;
  padding:1em;
  border:1px solid #ee7122;
  color:white;
  text-align: center;
  border-radius: 0px;
  -webkit-border-radius: 0px;
  background: rgba(255, 255, 255, 0.12) url("../img/arrowdown.png") no-repeat 90% 50%;
  background-size:10%;
}

self-explained.

To create an overlay network on multiple hosts over swarm, following are required:

• a key-value store service: this is used for broadcasting hosts / swarm agents. It can be same kv store swarm used for discovery
• Run docker daemon with following parameters:
  • cluster-store: where the store is
  • cluster-advertise: what network interface to be advertised
    Read More
    docker

According to this, do following to determine the client ipaddress:

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var ip = (req.headers['x-forwarded-for'] ||
     req.connection.remoteAddress ||
     req.socket.remoteAddress ||
     req.connection.socket.remoteAddress).split(",")[0];

Testing with web app is always fun. Angularjs makes it even better.
This quick note bootstrap any angular.js projects embracing with unit tests.

Tools

Unit testing in Angularjs is using (by default) Jasmine and Karma.

Also, angular-mocks needs to be installed. It is needed for injection and some other mock objects.

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bower install --save angular-mocks

According to mongoose.js doc, it is able to set setters to a field on schema.
However, the doc is not quite detailed and obselete.
Some example:

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var schema=new Schema({
  password:{
    type:String,
    required:true,
    set:hash
  }
})

function hash(plainPwd){
  return require("crypto").createHash("sha1").update(plainPwd).update(secret).digest("hex");
}