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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 apt-get...

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


  Linus Torvalds’s Lessons on Software Development Management


If anyone knows the joys and sorrows of managing software development projects, it would be Linus Torvalds, creator of the world's most popular open-source software program: the Linux operating system. For more than 20 years, Torvalds has been directing thousands of developers to improve the open source OS. He and I sat down to talk about effective techniques in running large-scale distributed programming teams – and the things that don’t work, too.Torvalds says there are two thing...

   Linux,Software development,Linus Tonalds     2011-09-28 09:16:02


  Using msmtp to replace sendmail


sendmail is a mail client in Linux with many vulnerabilities and tedius configuration steps, many system administrators have disabled using it. Then how do we know what happens if a crontab script executes with error? Actually there are some replacements for sendmail, one is ssmtp, but this application is no longer maintained, we even cannot find its source code on Google. Fortunately, we can use msmtp to replace sendmail. The address : http://msmtp.sourceforge.net/ 1. Installation After downloa...

   sendmail, msmtp, replacement     2012-09-27 11:41:48


  Using vi key bindings in bash and zsh


Takeaway: If you prefer to use vi or vim for command-line editing, you can configure shells to use vi key bindings instead of emacs-style key bindings. Here’s how. By default, most shells use emacs-style key bindings for command-line editing and modification. For users of vi or vim, however, you can instead configure shells to use vi key bindings instead. This is done by editing ~/.bashrc in the case of bash, or ~/.zshrc in zsh and ad...

   vi,Linux,Zsh,bash,key binding     2012-02-07 06:22:36


  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. Don't know the reason. 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 this...

   mcrypt,response,slow,solution     2012-09-27 12:03:16


  Computer skills one can learn within one day


Computer related technical skills are usually thought as complicated and difficult to understand. It's very difficult for one to get hands on one skill or master one skill. But if you really do want to learn something useful within one day, there are some good choices which will not take too long to get to know and use.. Version control:- Git, GitHub and SVN Regular expressions AWK sed Grep Learn how to do things with Vim that you never knew could be done. Set up a crawler that can scrape some ...

   Computer skills,Learn     2013-09-16 08:51:35


  Some measures for improving Linux server security


The hackers often exploit server weakness to gain access control to some servers. With a scanner, aimlessly looking undefended host, backdoor, control, and sold to people in need. Some basic security measures can be taken on Linux servers to avoid being attacked by hackers. Disable root remote login As the default administrative account, root is the account which is most likely to be attacked.Disabling ssh remote login is necessary. Method: Edit / etc / ssh / sshd_config PermitRootLogin no At t...

   Linux server,Server security     2012-08-21 05:08:50


  Command line todo list manager-- Taskwarrior


What is Taskwarrior? Taskwarrior is a task management tool in a terminal environment, it has powerful functions. Here is a short description about it from its official website: It maintains a task list, allowing you to add/remove, and otherwise manipulate your tasks. Task has a rich set of subcommands that allow you to do sophisticated things. You'll find it has customizable reports, charts, GTD features, device synching, documentation, extensions, themes, holiday files and much more. Installa...

   Taskwarrior,Task management     2013-08-12 23:44:20


  Time-saving tips Linux users should know


As a programmer or system administrator, we have more chances of working on *nix platforms. It's tough experience when first start use *nix as we need to face a black screen without knowing what's behind it. Now, if we can have some resources to rely on, then we will find the beautify of *nix. They are fast, efficient and most importantly sexy. Below are some great tips for helping Linux users get used to Linux. This list is a bit long. So be patient. To get more information on a command mention...

   Linux,Tips     2013-09-03 22:30:48


  Integer overflow


You may be familiar with integer overflow, but what you may not be familiar with is how gcc handles signed integer overflow. First let's look at the standard, for unsigned integer, the standard says : A computation involving unsigned operands can never overflow, because a result that cannot be represented by the resulting unsigned integer type is reduced modulo the number that is one greater than the largest value that can be represented by the resulting type. In other words, unsigned integer ov...

   Integer overflow,gcc,Linux     2012-10-20 13:33:10