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  Build Hadoop environment in Linux

Hadoop standalone installation: 1. Install JDK Install JDK with below command: sudo apt-get install sun-java6-jdk Configure Java environment, open /etc/profile, add below contents: export JAVA_HOME = (Java installation directory) export CLASSPATH =".:$JAVA_HOME/lib:$CLASSPATH" export PATH = "$JAVA_HOME/:PATH" Verify installation of Java Type java --version, if it outputs Java version information, then Java is successfully installed. 2. Install SSH Install SSH with below command: sudo ...

   Hadoop.Linux,Configuration     2013-07-31 23:22:27

  Push docker image to remote AWS ECR

With the popularity of distributed and large-scale systems, there are more and more adoptions of cloud services. One of the most popular container in the market is Docker and one of the most popular cloud service provider is AWS. From development perspective, there is frequent need to push local docker image to remote ECR for debugging or testing purpose. Normally when a code change is done and the committed change would go through a series of process like code review, push to remote repo, merge...

   CLOUD,AWS,DOCKER,AWS ECR     2020-12-13 04:12:26

  Different types of keystore in Java -- JCEKS

JCEKS stands for Java Cryptography Extension KeyStore and it is an alternative keystore format for the Java platform. Storing keys in a KeyStore can be a measure to prevent your encryption keys from being exposed. Java KeyStores securely contain individual certificates and keys that can be referenced by an alias for use in a Java program. The process of storing and loading different entries in JCEKS is similar to what JKS does. So please refer to the article Different types of keystore in Java -...

   Java,KeyStore,JCEKS,Tutorial     2015-01-05 00:30:56

  Common usage of ls command in Linux

In Linux, ls might be one of the most frequently used commands. It is used to list files in a specific directory. In most cases, we may just use ls -l to list the files under a directory. But have you explored other usages of this command. In this post, we will summarise some other common usages of ls command Assuming we have below directory structure in our system, let's see them using tree command. List details of the files If we want to list the details of the files in /home/alvin/test_...

   LINUX,SHELL,LS     2018-12-16 03:00:42

  Some tricks on PHP session

1. Session timeout problem There is a nuance we found with session timing out although the user is still active in the session.  The problem has to do with never modifying the session variable. The GC will clear the session data files based on their last modification time.  Thus if you never modify the session, you simply read from it, then the GC will eventually clean up. To prevent this you need to ensure that your session is modified within the GC delete time.  You can accomp...

   PHP,Session,Timeout,Solution,Various domain     2015-03-13 07:05:37

  New features in PHP 5.5

Just a few days ago, the PHP official website was redesigned. It seems we directly go from Web 1.0 era to Web 2.0 era. In addition to this new change, PHP 5.5 was also released. Some new features are added in this release. Here we summarize some of them. Enable OPCache by default When installing PHP 5.5, the Zend OPCache will be compiled as OPCache by default and OPCache is enabled by default. Some changes to the language itself Add Generator function getLinesFromFile($fileName) { if (!$file...

   PHP 5.5,New features,Generator     2013-07-05 03:13:22

  Different types of keystore in Java -- Overview

Keystore is a storage facility to store cryptographic keys and certificates. They are most frequently used in SSL communications to prove the identity of servers and clients. A keystore can be a file or a hardware device. Three are three kinds of entries can be stored in a keystore depending on the types of keystores. The three types of entries are: PrivateKey : This is a type of keys which are used in asymmetric cryptography. It is usually protected with password because of its sensitivity. It ...

   JAVA,KEYSTORE,OVERVIEW,JKS,PKCS12,JCEKS,PKCS11,DKS,BKS     2014-08-18 02:09:54

  Canonicalize XML in Java

XML canonicalization is often used when there is need to create digital signature to be sent to peers for verification. Since digital signature is created based on XML data, the XML data has to be canonicalized before its signature value can be calculated. Even an extra space may affect the signature value calculated, hence it must follow some rules to canonicalize the XML data so that it has a standard format. This is why W3C created specification Canonical XML Version 1.1. This specificat...

   JAVA,XML,JAVA SECURITY     2016-01-20 01:39:45

  Using htpasswd to protect your website in Nginx

We need to build a password protected website frequently such as an internal website within the team, demo website. Here what we are talking about is password protection in Nginx server level instead of application level registration and login. We are going to use Nginx server configuration and htpasswd file to achieve password authentication. The final result looks like below(Different browsers may have different interfaces): If the authentication fails, it will report a HTTP error: 401 Author...

   Nginx,Password protected,htpasswd     2013-06-07 21:35:27

  Get associated file icon with only extension name using C++ on Windows

I have searched on Google for a few examples on how to get associated file icon with only file extension name using C++ on Windows. There are some useful information provided on MSDN which explains the use of SHGetFileInfo() function.It also gives an example code, but it doesn't say how to do it with only the extension name.  Here I give an example code on how to achieve this after I gathered and summarized some  useful information from Internet. I have tested the code on my PC, it w...

   File icon,Windows,Association,Extension name,C++     2012-03-26 09:55:20