Category: linux

How to create a Docker base image

Here is a compelete set of instructions to create your own Docker base image. Docker base images are the first layer in a Docker image. There are plenty of base images available, however you can create your own if you like as well. First,…

Copying files in Linux

Copying files should be simple, yet there are a number of ways of transferring files. Some of the ways that I could think of are listed here.

IP Header Explained

Mininum 20 bytes, maximum 60 bytes. Maximum size is 65,535 bytes for IP header + data. – Version field (4 bits) for IPv4 or IPv6 – IHL or Internet Header Length (4 bits), it is the number of 32-bit words in the header –…

Extending VM LVM disk

I have a CentOS VMs running in VMware, one of the VMs I was running was out of disk space. The disk was originally 85GB, I tried to increase it to 345GB. In an effort to increase the disk size, I tried: Shutdown the…

High Availability using Keepalived

HAProxy (http://haproxy.1wt.eu/) is a popular solution for load balancing servers. In a typical load balanced configuration, there may be a number of web servers behind a pair of HAProxy load balancers. The question arises, how do you load balance the HAProxy servers themselves? One…

Git on CentOS

Git is very popular source code management (SCM) system. It has replaced SVN as the preferred choice of coders. In this brief tutorial I will show you how to setup Git on your CentOS box, and start using it. First, install Git from source…

Linux troubleshooting tools

An app is running “slow” on Linux, how do you go about figuring out what could be wrong? Typical bottle-necks for a slow application are cpu, disk i/o, network, memory, or database. For instance if Apache is running slow it could be memory starved….

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