SEARCH KEYWORD -- LINUX KERNEL


  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

  Recover deleted file in Linux EXT3 file system

Environment : CentOS 5.3 x86_64, /dev/sdb1 is the data segment /data0. EXT3 file system. Problem : /data0/tcsql/cankao/phpcws-1.5.0/httpcws.cpp is deleted mistakenly and httpcws.cpp is not backed up. It will take much time to rewrite this program again. So we must recover it back. debugfs is feasible in EXT2 file system, but in EXT3 file system, it's not very useful. There is one open source software called ext3grep which can help us recover deleted file in EXT3 file system. The recovery steps a...

   Linux,EXT3,File recovery     2013-08-16 07:06:45

  Unix directory hierarchy history

As a beginner user of Unix or Linux, people would frequently get confused about the use of different directories of the system.  For example, there is a /bin directory under root(/), it is used to store binary files. However, there are /usr/bin and /usr/local/bin under /usr which are used for storing binary files as well. Some systems even have /opt/bin. What are the differences among them? Though there are articles explaining different directories in *nix such as Filesystem Hierarchy Stan...

   UNIX,LINUX,FILESSYTEM,DIRECTORY HIERARCHY,HISTORY     2016-10-21 23:47:17

  Handle NXDomain error when resolving IP address in Ruby DNS resolver

In another post, we covered how to resolve SystemStackError when resolving IP address in Ruby. In this post, we would cover another common issue where a NXDomain error is returned when resolving an IP address. The NXDomain error means that the queried domain name does not exist in the DNS. In Ruby, DNS resolver library will use /etc/resolv.conf by default get the name servers to resolve the domain name. There are multiple DNS name servers can be specified in /etc/resolv.conf with below format. ...

   RUBY,RUBY ON RAILS,NETWORK,DNS,NXDOMAIN     2017-07-16 01:39:23

  How to check which Ohai plugin hangs in chef client run

Ohai plugins are very important components in chef client which aims to provide resource management automation on a server. The data discovered by Ohai plugins are describing the current state of the server and they will be used to maintain the server in a desired state. Each Ohai plugin discovers a specific pierce of information about the server such as cpu, memory, middleware etc. However, there are rare occasions(well I am a bit optimistic here) someone may find that the chef client...

   HOW TO,CHEF-CLIENT,OHAI,UPTIME,HANG     2017-12-24 22:09:59

  Build RPM package on Linux

1. Check the OS version and core version #uname -a #more /etc/redhat-release 2. Create relative directories /usr/src/redhat/SOURCES    //Store source codes, patches, icons etc /usr/src/redhat/SPECS        //Store specs about the process of building RPM packages /usr/src/redhat/BUILD     //File after uncompressed are stored here /usr/src/redhat/RPMS     //Store the binary files built with rpmbuild /usr/src/redhat/SRPMS&nbs...

   RPM,Linux,Build     2013-03-22 12:44:29

  HeartBleed: Inside the heart, what happens to a normal WEB user?

To be brief, our email, IM, facebook etc. are at the risk, so try to minimize the access in these few days. Especially we should try to avoid log into our internet-banking, because we may expose our user id and password. Also later when the service providers fix the bug, we would better to change a new password for all the web accounts that are important to us. Here comes the technical explanation. You might notice before that a lot of websites use URL starting with "https". For example, https:/...

   HeartBleed,Analysis     2014-04-09 22:41:43

  Problem and Solution for Installing wxPython on Ubuntu 20.04

When we try to install wxPython lib on Ubuntu system to do software GUI development, most of time we may meet some installation and lib dependency problems. For the latest Ubuntu version, the problems still happen. Below are some common problems which happened frequently and their solution: --------------------------------------------------------------------------------------------------------------- Problem [1]: Install wxPython on Ubuntu 20.04 fail because of dependency package Gtk is not in...

   PYTHON,WXPYTHON,UBUNTU 20.04     2020-09-09 05:32:35

  Want to install 64 bit OS on VirtualBox?

By default, VirtualBox only allows to install 32 bit OS on it. But sometimes, 64 bit OS is wanted for specific uses such as running platform specific tests. To allow installing 64 bit OS on VirtualBox. Below information is needed. Here is the official documentation about 64 bit OS: VirtualBox supports 64-bit guest operating systems, even on 32-bit host operating systems, provided that the following conditions are met: You need a 64-bit processor with hardware virtualization support (see the ...

   VirtualBox,64 bit,hardware virtualization,Ubuntu     2014-11-08 03:52:07

  Significance and use of do{...}while(0)

In some Linux kernel and other open source codes, we can see some codes like below: do{ ... }while(0) This code snippet is not a loop, it seems there is no significance of using do...while this way, then why should we use it? In fact, the significance of do{...}while(0) is better than optimizing your code. After some research, we summarize some benefits of it. 1. Help define complex macro to avoid error #define DOSOMETHING()\ foo1();\ foo2(); The me...

   do{...}while(0), optimization     2012-10-21 21:13:22

RECENT