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  Use DTrace to diagnose gdb issues


A few days ago, I installed the newest 64-bit gdb program (version 7.7.1) on Solaris 10 (X86_64 platform) to debug programs. After playing with the gdb a day, I found 2 issues about gdb:(1) The "set follow-fork-mode child" command doesn't take effect. By default, after the parent process forks the child process, the gdb will track the parent process, so this command can make gdb begin to follow the child process. But this command works OK on Linux.(2) The gdb can't parse the 32-bit application c...

   DTrace, debug, gdb, UNIX     2014-06-28 05:11:20


  Use progressive JPEG to improve user experience


JPEG image files can have two different save types : Baseline JPEG and Progressive JPEG. Both of them have the same extension name but with different display effect. Baseline JPEG This type of JPEG files are scanned from top to bottom consecutively, each line of the image data will be saved sequentially. When opening this kind of images, data will be displayed with the save order line by line until all the data are read. If the image size is very large or network speed is very slow, the image wi...

   USER EXPERIENCE,PROGRESSIVE JPEG,BASELINE JPEG     2013-07-25 08:11:50


  How to secure an Ubuntu Apache web server


Securing server software is not a straightforward task. Not all of our operating environments are the same, leading to a variety of potential security vulnerabilities. However, using a few basic configuration and security options, you can stay a little ahead of where you want to be. 1. Fail2ban Fail2ban is a Python-based intrusion prevention software that detects and blocks malicious IP addresses from multiple unsuccessful attempts at software logins. In other words, if someone is attempt...

   Unix server security,Log,.htaccess,Cache     2011-12-27 09:25:32


  Server monitoring shell scripts


There are many open source server monitoring software such as cacti and nagios. Besides these, can we write our own shell scripts to monitor them? The shell scripts written by ourselves can fulfill our special requirements better and have a more detailed coverage. Below are some commonly used shell scripts used by Evangelist, an Oracle DBA. 1. Check network gateway traffic #!/bin/bash #network #Mike.Xu while : ; do time='date +%m"-"%d" "%k":"%M' day='date +%m"-"%d' rx_before='...

   Server monitor,CPU,memory,shell     2013-08-30 21:56:14


  HeartBleed: Inside the heart, what causes the bleeding?


Just after a few weeks since Apple's famous goto fail bug, there is one bug in OpenSSL which catches the attention from the world again. The bug is named HeartBleed, found in OpenSSL library, a famous open source library supporting lots of  SSL/TLS communication among server/client applications. The reason why this bug catches the attentions from the world is it affects almost all sites which are using the affected OpenSSL library, these includes many applications like Nginx server, some v...

   OpenSSL,HeartBleed     2014-04-09 05:47:30


  10 tools to make your shell script more powerful


Many people mistakenly think that shell scripts can only be run in command line. In fact shell can also call some GUI components such as menus,alert dialogs, progress bar etc. You can control the final output, cursor position and various output effects. Here we introduce some tools which can help you create powerful, interactive and user friendly Unix/Linux shell scripts. 1. notify-send This command can let you inform the process to send a desktop notification to users. This can be used to send ...

   shell,GUI,zenity     2013-04-05 08:50:41


  Set file permission in Java


Prior to Java 6,  there is no good solution at the Java level to provide file permission management. You need to implement your own native methods or call the Runtime.exec() to invoke the system routine such as chmod in LInux. Since Java 6, Java introduces a set of methods which can be used to set the file permission at Java level. These methods include: File.setReadable(boolean); File.setWritable(boolean); FIle.setExecutable(boolean); File.setReadable(boolean, boolean); File.setWritable(bo...

   JAVA, FILE PERMISSION, POSIX,learnjava     2015-08-29 03:37:37


  Why every programmer should learn Python or Ruby


If you are a student, you probably know C, C++ and Java. A few know VB, or C# / .NET. At some point you’ve probably built some web pages, so you know HTML, CSS and maybe JavaScript. By and large, it is difficult to find students who have any exposure to languages beyond this. And this is a shame because there are a number of programming languages out there which will make you a better programmer. In this article, we give some reasons why you must learn Python or Ruby2. Compared to C/C++/...

   Python,Ruby,Advantage,JavamCmDusadvantag     2011-07-25 08:41:42


  GitHub : Code is the most direct way for programmers to communicate


If not invested by Andreessen Horowitz, GitHub might not be noticed by Forbes, CNN, New York Times. People didn't know this tool because it was very far away from the world -- GitHub is a project hosting service used by programmers.But to some programmers, it is not just a place for project hosting, it is`also the hub for open source projects, a place for programmers improving themselves and a social network for programmers.There are around 3.26 million projects hosted on GitHub currently, inclu...

   GitHub,Open source,Hosting,Social     2012-07-20 11:38:31


  The craziest Javascript implementations


Since its birth in 1994, Javascript has come a long way. Today it’s one of the most popular programming languages on the web because of high popularity of AJAX based web-applications. Also the rise of micro-frameworks such as jQuery (also Prototype, Moo Tools etc) which have reduced dramatically the complexity of code developers needed to write, it is well tested, has a ton of plug-ins, has a large development community and reduced development time.And lately even Server-Side J...

   JavaScript,Crazy implementation,JVM,Turing machine     2012-01-03 12:09:42