Category Archives: Featured

awk Commands, Examples & Meaning

Learn to use awk for text and data extraction, data processing, validation,  generate reports for analysis, automation with with the help of examples of if else , compare & arrays plus regular expressions & built in operational variables, meaning, examples &command syntax.

Application Monitoring

Application monitoring

Application monitoring is a very important aspect of a project but unfortunately not much attention is paid to develop the effective monitoring while the projects are still movingh to completions. Once project is complete & live lack of proper monitoring costs in terms of downtime when support persons are not aware if application is having some problems or application not working at all.

Linux & Unix Date Format Examples

Learn about Linux and Unix date & time formating with the help of simple explanation and added example. Date command in Unix & Linux is used to format date as well as time. First portion of this article covers Date  function and the second portion has the  time function covered.

ssh Without Password in Few Simple Steps

How to configure passwordless ssh &sftp access in Unix & Linux systems? Follow these simple steps with examples with a basic troubleshooting section at the end. sftp uses underlaying ssh access for authentication and after you establish passwordless ssh access you will have passwordless sftp access as well.

This a real life example of configuring passwordless access for two users . The user ‘web’ in this case needs a secure password less access to another user james in a server ‘devserver’
.

Unix Tutorial – Learn Unix OS Basics to get started

This is a Unix Tutorial where you can learn Unix OS Basics to get started with UNIX and Linux operating systems and covers Unix Directory structure , Unix Commads and Unix Shells

Crontab – Quick Reference

Setting up cron jobs in Unix, Solaris & Linux

cron is a unix, solaris, Linux utility that allows tasks to be automatically run in the background at regular intervals by the cron daemon. 

Unix Commands Tutorial

Learn about the Unix commands with their usages and examples.
This Unix command tutorial introduces you with some of the most popular and useful commands used in nix operating system to get you started with Unix.
All Unix OS comes with online manual system, man, which can be used used as ,man , to get more details and complete set of options.

vi editor Quick Reference

 

Introduction

Learn about the default text editor, vi, pronounced as ”vee eye”, in Unix, Linux and other Unix like systems. A short, concise vi quick reference lets you get started with vi today. Explains vi editor mode &  vi commands with examples for editing in vi.

Backup Commands in Linux & Unix with Usage and Examples

Unix and Linux backup and restore can be done using backup commands tar, cpio ufsdump, dump and restore. Though these commands may be sufficient for small setups in order to take a enterprise backup you have to go in for some custom backup and restore solutions like Symatic netbackup, EMC networker or Amanda.
Any backup solution using these commands depends on the type of backup you are taking as these backup commands offers different capabilities.

DNS Troubleshooting

DNS troubleshooting , this article describes some of the common dns problems and their solutions.
First phase of article describes dns errors relating to configuration , server setup and its basic functionality . Second phase talks about the nslookup related errors when the dns servers seems to be working correctly but names resolution fail .

fsck – Check & Repair Unix and Linux File Systems

fsck, similar to chkdsk in windows, checks and repairs the file system in Unix & Linux operating systems. Learn about fsck modes, phases & fsck errors messages

fsck, File System Consistency checK, is a system utility in Unix, Linux and other Unix like systems for checking and repairing file system inconsistencies.

File system can become inconsistent due to several reasons and the most common is abnormal shutdown due to hardware failure, power failure or switching off the system without proper shutdown. Due to these reasons the superblock in a file system is not updated and has mismatched information relating to system data blocks, free blocks and inodes.

fsck in Linux

fsck in this document is refered with reference to ufs file system but it can be used in Linux systems as

fsck -t ext2 /dev/sda3
or
fsck.ext2 /dev/sda3
fsck.ext4 /dev/sda3
fsck.ext3 /dev/sda3

it returns with any of the followig code

0 – No errors
1 – File system errors corrected
2 – System should be rebooted
4 – File system errors left uncorrected
8 – Operational error
16 – Usage or syntax error
32 – Fsck canceled by user request
128 – Shared library error

fsck checks the file systems defined in /etc/fstab in Linux and /etc/vfstab in Unix systems