VIM cheat sheet

< The list of Vim commands > Working with files Vim command Action :e filename Open a new file. You can use the Tab key for automatic file name completion, just like at the shell command prompt. :w filename Save changes to a file. If you don’t specify a file name, Vim saves as the file name […]

List interfaces and IPs neatly

The following command gives a neat list of the Devices and their IPs / details without all the gruesome details. ifconfig | egrep  "Link|inet" A sample result would be: [root@testarossa-00-0c-29-47-8f-35 vm]# ifconfig | egrep "Link|inet" eth0 Link encap:Ethernet HWaddr 00:0C:29:47:8F:2B inet addr:192.168.47.135 Bcast:192.168.47.255 Mask:255.255.255.0 eth1 Link encap:Ethernet HWaddr 00:0C:29:47:8F:35 inet addr:192.168.1.71 Bcast:192.168.1.255 Mask:255.255.255.0 lo Link […]

Dsabling SElinux In Centos

Sometimes and with some DB platforms especially when you are testing and want to reduce the number of variables during development, testing etc.. you don not want SELinux watching your back. While it is a must to enable SELinux in hardened production systems it can be quite a pain to handle. Sometimes it needs disabling […]

Slash notation lookup table

Total-addresses: how many unique addresses can be represented. To determine how many are available to be assigned to devices you need to subtract 2 from the provided number to allow for the ‘network’ and ‘broadcast’ address. A further one of these may need to be assigned to a router. Net bits Subnet mask Total-addresses /20 255.255.240.0 4096 /21 […]

Introduction to APT (advanced package Tools)

Advanced Packaging Tool Ubuntu — and all Debian-based distros — includes the Advanced Packaging Tool (APT), which can be used to easily download and install software for the operating system. This article looks at APT, and how it is used. Topics : Table of Contents Installing Software on a Computer Installing Software on Windows Installing Software on […]

Introduction to Yum

1. Introduction   Yum is a tool for automating package maintenance for a network of workstations running any operating system that use the Red Hat Package Management (RPM) system for distributing packaged tools and applications. It is derived from yup, an automated package updater originally developed for Yellowdog Linux, hence its name: yum is “Yellowdog Updater, Modified”. Yup was originally […]

The /etc/passwd File Format

The /etc/passwd file stores essential information, which is required during login i.e. user account information. /etc/passwd is a text file, that contains a list of the system’s accounts, giving for each account some useful information like user ID, group ID, home directory, shell, etc. It should have general read permission as many utilities, like lsuse […]