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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

  How to use xargs command in Linux

What is the xargs command? The xargs command constructs and executes commands provided through standard input. It takes input and converts it into command arguments for another command. This functionality is particularly useful in file management and can be combined with commands like rm, cp, mkdir, and others. Using the xargs command When used alone, the xargs command prompts the user to enter a text string and then passes it to the echo command. This example demonstrates the input provided an...

   XARGS,LINUX     2023-11-17 11:19:41

  One reason why mcrypt responds slowly

This morning one colleague came over and talked about one script which used mcrypt responded very slowly, the server configurations are fine. But the reason for the slowness is unknown. Here is one script which reproduces the issue: <?php $dmcryptText = "dummy"; $key = "foobar"; $size = mcrypt_get_iv_size(MCRYPT_BLOWFISH,MCRYPT_MODE_ECB); $iv = mcrypt_create_iv($size); //Take care $m = mcrypt_ecb(MCRYPT_BLOWFISH, $key, $dmcryptText, MCRYPT_DECRYPT, $iv); var_dump($m); When 20 requests of&...

   SOLUTION,SLOW,MCRYPT,RESPONSE,PHP     2012-09-27 12:03:16

  Install and setup Kafka on Windows

Kafka has become a very popular distributed message delivery service which decouples different services while making message delivery between service easy, fast and reliable. In this post, we will walk through how to install and set up Kafka on Windows. Pre-requisite Java Apache ZooKeeper Installation Go to Kafka's download link and download the latest stable release, we downloaded 2.2.0 as of this writing. After downloading, copy the installation file to some folder and unzip it.  Sinc...

   KAFKA,STREAM,USER GUIDE     2019-06-01 02:12:07

  Useful git commands in daily work

In a developer's daily work, it is frequent to see lots of commits made. It would be a headache if one cannot use git commands well especially when in cases where some fixes need to be made on existing branches. There are some frequently used command such as git pull, git merge and git push. Apart from these, there are some other practical commands which may be useful for real use cases. This post will try to list some of them. git grep  It will lists all files containing the searched keywo...

   GIT,GIT COMMAND,GIT LOG     2022-05-01 03:17:15

  Oracle database to execute multiple statements at command line

Oracle database is now a mature and popular RDBMS which is used by lots of enterprises. With its evolution, many utilities and applications are developed around it as well. Now Oracle database also provides cloud support. As a DBA, managing Oracle database is daily routine work and some tools may be used frequently. One of them is sqlplus, the command line tool for executing SQL command. sqlplus is installed while the Oracle database is installed. To start sqlplus, one just needs to open a termi...

   ORACLE,ORACLE DATABASE,SQLPLUS     2016-12-09 20:11:28

  Install and setup vsftpd on AWS server

When developing websites, frequently we may need to upload source codes to the remote server. To ease of thew work, many website developers set up FTPs to upload the files. This post is a tutorial on how to install and setup vsftpd on a server. vsftpd is a very popular FTP service on Unix-like systems. Open command terminal, then install the vftpd by issuing command yum install vsftpd or sudo apt-get install vsftpd After installing the vsftpd, the config file needs to be updated based on the ope...

   FTP,vsftpd,AWS,Passive,Active     2015-02-02 02:20:27

  Using keytool to create certificate chain

JDK provides a command line tool -- keytool to handle key and certificate generation. This tool has a set of options which can be used to generate keys, create certificates, import keys, install certificate and export certificates etc. In this tutorial, we will show how to create certificate chain using keytool. If you want to understand how to create certificate chain programmably, please refer to Generate certificate in Java -- Certificate chain. To begin, we first generate a key pair whi...

   JAVA,KEYTOOL,CERTIFICATE CHAIN,CERTIFICATE     2015-12-17 07:09:33

  Output control functions in PHP

The Output Control functions in PHP allow you to control when output is sent from the script. This can be useful in several different situations, especially if you need to send headers to the browser after your script has began outputting data. The Output Control functions do not affect headers sent using header() or setcookie(), only functions such as echo and data between blocks of PHP code. These output control functions include ob_start(0, ob_clean(),ob_get_contents(), etc. To be honest, I a...

   PHP,output buffer,relationship,ob     2012-06-15 10:11:58

  A trick of building multithreaded application on Solaris

Firstly, Let’s see a simple multithreaded application: #include <stdio.h> #include <pthread.h> #include <errno.h> void *thread1_func(void *p_arg) { errno = 0; sleep(3); errno = 1; printf("%s exit, errno is %d\n", (char*)p_arg, errno); } void *thread2_func(void *p_arg) { errno = 0; sleep(5); printf("%s exit, errno is %d\n", (char*)p_arg, errno); } int main(void) { pthread_t t1, t2; ...

   C, Solaris     2014-10-14 02:59:40