Generate E-mail Alert Whenever An User Is Added

Recently I came across a situation wherein there was a requirement to trigger an email alert whenever a new user is added to the system (Linux). By default an alert would get logged in "/var/log/secure" file as and when a user is added or removed. However, I wanted a similar e-mail alert to be sent. Hence, I thought of coming up with a script to get this done. I found that this can be achieved in 2 ways as explained below (there could many other ways as well):

Lets Automate Kdump

Kdump is a kernel crash dumping mechanism and is reliable because the crash dump is captured from the context of a freshly booted kernel and not from the context of the crashed kernel. Kdump uses Kexec to boot into a second kernel whenever system crashes. This second kernel, often called a capture kernel, boots with very little memory and captures the dump image.

Create & Restore Linux System Data Using Dump Command

I was searching for a simple backup solution in Linux system that could serve in block-level backup and for disaster recovery as well, and yet simply cost effective. Now-e-days, one could see a lot of options, however, I wanted to try out simple and yet native Linux solution, so, I came across this "dump & restore" utility.  This may not be an ideal solution for a larger network, but one could leverage on this for smaller network wherein there is no tight schedule on recovery. So, I thought of creating a step-by-step document of the same.

Complete system can be backed up and restored using native Linux commands “dump & restore” which would facilitate backup or disaster recovery process.

Rear- Linux Disaster Recovery Solution

 “Rear” (Relax-and-Recover) fits perfect in implementing a bare metal disaster recovery solution & image migration as well.  Rear is the leading Open Source disaster recovery solution. It is a modular framework with many ready-to-go workflows for common situations.

Most backup software solutions are good at restoring data but do not support recreating the system layout. Rear is good at recreating the system layout but works best when used together with supported backup software. In this combination Relax-and-Recover recreates the system layout and calls the backup software to restore the actual data. Thus there is no unnecessary duplicate data storage and the Rear rescue media can be very small.

Kickstart Implementation In Linux Without PXE

Steps of doing automated kickstart installation on RHEL systems  without  PXE boot and using static IP address.

Some Key Points:-

- Kickstart is ideally be suited for DHCP based environment with PXE enabled network cards.

- If there is no PXE enabled network card then initial manual effort is required.

- Kickstart would use NetworkManager (NM) daemon for initial fetch of “*.cfg” file and boot files over network.

Main Differences Between Linux & Solaris

	Linux	Solaris
Default Shell	/bin/bash (/bin/sh would typically symlinked to bash)	/bin/sh
File System	Ext2/3/4 or XFS (RHEL 7)	UFS - Unix File System and VxFS,QFS & ZFS (Solaris 10 onwards) also supported.