On Oct 2, Linus Torvalds proudly announced the release of Linux 4.8. But just days after the release, a bug was found in the kernel and Linus came out and apologized for this bug.I'm really sorry I applied that last series from Andrew just before doing the 4.8 release, because they cause problems, and now it is in 4.8 (and that buggy crap is marked for stable too).In particular, I just got this kernel BUG at ./include/linux/swap.h:276 and the end result was a dead kernel.The bug that commit 22f2ac51b6d64 ("mm: workingset: fix crash in shadow node shrinker cau...

SSH is a popular cryptographic network protocol for secure network service operation. It is frequently used in remote server login. For a system administrator or software developer, SSH is frequently used to access remote servers or development servers or testing servers etc. To login with SSH, there are different authentication mechanisms : password, public key and interactive etc. If a remote server needs to be accessed frequently, password authentication may be too troublesome as password needs to be typed every time. In this scenario, public key authentication would be a life sav...

JSON now becomes a very popular data format because of its simplicity and light-weight. Nowadays many RESTful APIs will offer a choice of exchanging JSON data between the server and client. Sometimes the data may not be formatted and it cannot be easily read by human beings. It's frequently desired that the unformatted JSON data should be formatted before read.Today we will show a few ways to format JSON data on Ubuntu. Assume we have a json file test.json with below content.{ "title": "Test", "description": "Sample description" }The normal cat command will output below content.postman@postman...

This is a Q&A post after sharing Guide for installing Ubuntu in VirtualBox on Windows1. If the resolution of the installed guest OS on the VirtualBox is too small(For example 640x480) and you cannot adjust it through System Settings -> Display, what should you do?A: In this case, it is mostly probably you don't have the VirtualBox Guest Additions installed. You can install the Guest Additions on your guest OS by:sudo apt-get install virtualbox-guest-dkmsThen restart the VM and you will see the resolution you want.2. How to share a folder from guest OS to host OS. The guest OS is Ubuntu ...

Previously we showed how to install Ubuntu in VirtualBox. What if we want to communicate with the host OS from within the Guest OS on VirtualBox? There are a few ways to do this. For example, bridged network, Host only networks. Today we will show you how to enable network communication between host OS and guest OS using host only networks.A host only network will not need to access the physical network interface of the host OS. It will create a network between different virtual machines and the host machine. This is very useful if you want to set up a network of machines which just need to co...

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 commandyum install vsftpdorsudo apt-get install vsftpdAfter installing the vsftpd, the config file needs to be updated based on the operating mode preferred. The first thing to be done is to disable the anonymous login in vsftpd.conf# Disab...

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 section called “Hardware vs. software virtualization”).You must enable hardware virtualization ...

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 core dump file. Per my understanding, the 64-bit gdb should parse both 32-bit and 64-bit core dump fi...