Having to go the the server room to reset servers is the most headache thing for admins managing a cluster of Linux servers in a remote site. Either you can ping the server but can not ssh to it, or you even can not ping it. There are various reasons that may cause a Linux…
In Extending a Mounted Ext4 File System on LVM in Linux, we introduced how to extend a mounted ext4 filesystem on LVM Logical volume by adding a new physical volume. It is also common to shrink an ext4 file system as to spare some disk space. In this post, I will discuss how to shrink…
A pop-up terminal is great and handy on Linux and similar OS. On KDE, Yakuake is great. On Gnome or GTK, I ever tried Guake. It is quite good. However, it has not been as mature, stable and figure-rich as gnome-terminal. One day, I got this idea: why not using a script/program to manage the…
WhatsApp is a great messenger app on smart phones. There was ever some tricks to install WhatsApp app on iPod Touch or iPad. However, it is not possible now. But the good news is that the WhatsApp web is available so that users can use WhatsApp inside of a browser and the iPad or iPod…
If your website uses a self-signed certificates, Chrome will show a warning every time and you need clicks to continue. In this post, I will introduce how to make Chrome accept self-signed certificates for sites on Linux. This post is made short on purpose and you need to search the Web and learn if you…
My best favorite disk partition table manipulation tools are cfdisk/fdisk on Linux. However, for large disks, cfdisk/fdisk (of the versions by this post is written) will just give up with a message suggesting GPT partition table format and using GNU parted like WARNING: The size of this disk is 6.0 TB (6001042391040 bytes). DOS partition…
MPlayer is a great movie player. SSH is a great tool to connect and transfer data over the network securely. Combining these 2 great tools together will be greater. You may already has a small server storing some movies or videos or music and playing them on your laptop will be convenient. In this post,…
The posix_spawn() and posix_spawnp() functions create a new child process from the specified process image constructed from a regular executable file. It can be used to replace the relative complex “fork-exec-wait” methods with fork() and exec(). However, compared to fork() and exec(), posix_spawn() is less introduced if you search on the Web. The posix_spawn() manual…
Hadoop 2 or YARN is the new version of Hadoop. It adds the yarn resource manager in addition to the HDFS and MapReduce components. Hadoop MapReduce is a programming model and software framework for writing applications, which is an open-source variant of MapReduce designed and implemented by Google initially for processing and generating large data…
LVM is a great tool to manage hard disks on Linux—you can abstract the hard drives away and manage logical volumes from volume groups, you can dynamically add or remove hard drives while the file systems on the logical volumes need not to backed up and recovered, and you may create many snapshots of the…
Ctrl keys are important and possibly most frequently used in Emacs. However, it is painful on today’s common PC keyboards since Ctrl keys are usually in the corner of the keyboard main area. Why the key mappings in Emacs are designed like this? After it was designed, Emacs was commonly on the Lisp Machine keyboards…
git merge is frequently used during development of projects managed by git. There are many common questions about git merge and I find most are solved and discussed on StackOverflow. Here, I summarize useful ones so that others who want to learn git merge need to do the search again. Merge, rebase, fast forward and…
In this post, creating a file-backed virtual block device (VBD) and installing Fedora 20 in the Xen DomU via internet will be introduced. This domain is created on a Fedora 20 Dom0 as introduced in https://www.systutorials.com/installing-xen-on-fedora-20-as-domain-0/. For better performance, you may consider using LVM backed VM. Create file-backed VBD The actual space of VBD will…
I ever introduced [[installing-xen-domain-0-on-fedora-17]] as the first try to use the xen package delivered from Fedora and get away from manually compiling Xen and patching the kernel. In this post, I introduce installing Xen Dom0 on Fedora 20. Installing Xen First, install the xen pacakges: # yum install xen The Linux kernel is already ready…
It is common to set up git servers to host git repositories. Branching is lightweight in git and a very friendly mechanism to manage code. Here, I summarize a cheatsheet of common git branching commands for working on repositories from a git server. This post assumes that you have basic knowledge with git. If you…
It is continuously discussed that some Fedora users do not like the font rendering in Fedora Linux and there are solutions to improve the font rendering with potentially non-free or non-licensed software/fonts. However, with only the open source fonts and software and little tricks, the font rendering on Fedora can be quite good. In this…
Thunderbird automatically wraps lines by 72 characters by default. But wrapping in 72 characters may not look well on all clients. We may want Thunderbird not to wrap lines and let the receiver’s email client to choose the length to wrap lines. This post introduces how to make Thunderbird not wrap lines automatically. First, open…
Programs may want to catch the kill signals sent by the kill command in C programs on Linux so that it can gracefully shutdown itself before it is killed. For example, I have a daemon progd running, and it may be killed by pkill progd. The progd may want to save some in-memory state to…
VMware Player and VirtualBox are two cool and free full virtualization solutions and both can run on top of a Linux host. In this post, I introduce how to install, run, and uninstall VMware Player and VirtualBox on Fedora Linux. VMware Player Install VMware Player Download the installation bundle from VMware’s website. For example, the…
git is a great tool and it is common to have a git server over SSH possibly managed by gitolite. However, there are situations that we can not directly connect to the git server but be able to SSH to another node that can connect to the git server. The git server may allow only…