Category Archives: Basics
Bash is a Unix/Linux command interpreter (shell). Bash is the Bourne Again SHell created as part of GNU Project. Bash is an Bourne shell compatible shell that incorporates useful features from the Korn shell (ksh) and C shell (csh). It offers functional improvements over Bourne shell for both programming and interactive use. In addition, most Bourne shell scripts can be run by Bash without modification. Bash is intended to conform to the IEEE POSIX P1003.2/ISO 9945.2 Shell and Tools standard.
Bash was originally written by Brian Fox of the Free Software Foundation. The current developer and maintainer is Chet Ramey of Case Western Reserve University.
The improvements offered by Bash include:
- Command line editing
- Unlimited size command history
- Job Control
- Shell Functions and Aliases
- Indexed arrays of unlimited size
- Integer arithmetic in any base from two to sixty-four
Here are the top 10 Bash Programming Guides, Reference & Tools
Control M ( ^M) characters are introduced when you use lines of text from a windows computer to Linux or Unix machine. Most common reasons are when you directly copy a file from a windows system or submit form data copied and pasted from a windows machine.
Detecting ^M characters
^M is non printable character and often becomes difficult to find, in order to see if your file contains any non printable character use the cat command with -v option
$cat -v filename
Methods to remove ^M
In all these method , real secret is not to type ^M using keyboard but rather typing in control key sequence to get the ^M control character.
Shell has several special positional parameters which can be referenced but can not be assigned. These are used to process command line arguments in a shell script, to get process status, exit status and options flag.
These positional parameters can be assigned to a variable and values can be used for further processing.
$0 , $1 $2 $3 … parameters
These are special parameters and and has specific meaning according to the number. These parameters are useful if you want to validate executing file name and do the processing based on the arguments.
$0 : Shell argument 0, It expands into bash script file name or bash shell.
$1 $2 $3 … : Shell argument number : Used to get the specific argument from the script.
for example let’s create & execute the test script with some parameters :
find command is one of the important command in Unix and Linux used to locate the program, text, data , log config files for execution, viewing , editing renaming deleting etc. etc.
find command can find files based on many file attributes besides just the file name and here are the fifteen file attributes which you can use to find a file or files and here are 14 ways to find files in your unix and linux system.
Installation and Configuration of RHEL 7.x
Learn about Installation and initial configuration of Red Hat Enterprise Linux, RHEL 7.3
For this Linux step by step installation guide we will use RHEL 7.3 64Bit iso image, the installation procedure is same for all RHEL 7.x releases in case you want to use a different RHEL version to install.
Here are the 10 Steps to Install RHEL 7.x distribution.
netstat is a command line utility in Unix, Linux and Unix like systems to show information about
- network connections,
- routing tables,
- interface statistics,
- mas-querade connections
- multicast memberships
By default, netstat displays a list of open sockets of all configured address families , tcp , udp etc.
netstat provide very extensive network details and here are the top netstat usage with different options to get you the just the information you need.
Strategy, business models, and tactics are often used interchangeably but they differ slightly in their actual meaning. Business model is the means of identifying a solution’s key offerings that will make customers pay for the product/service.
Business model is defined at the outset, when the enterprise mobility solutions are discussing a potential application idea. It is crucial to get all aspects of the business model right, and the ambiguities (if any) listed and categorized as ‘needed to be addressed before development’ or ‘can be expounded on later’.
What is chmod ?
chmod ( Change Mode ) is a command line utility in Unix , Linux and other Unix like systems to change the read, write, execute permissions of a file for owner , group and others.
How to use chmod?
Chmod command is used in two ways :
1. Using octal value & position : Sets the permission for owner, group and others with octal values , 4 for read , 2 for write , 1 for execute and any sum of these number to get cumulative permissions.
man command, short for manual, provides help for the commands, utilities or function in Linux and Unix systems. Learn about usage , related packages, sections and other interesting facts about man pages.
Learn about the Solaris 10 & 11 certification , price, number of questoons , duration and direct links to official site for exam 1z0-876, 1z0-821 and more.
All the Linux distributions are either derivative of GNU/Linux ( OS made up of Linux Kernel developed by Linus Torvalds and GNU software repository) or derived from other Linux derivatives.
Desktop distributions comes with Graphical user interface enabled by default & aimed at individual users and most of the administration work can be done using GUI. Good for new users and running Linux-based graphical applications.
Server Distribution are for more advanced users who are familiar with Linux command line as Graphical Interface is not enabled by default in most of the server distributions. Server distributions comes with web servers like apache and networking packages like DNS and useful for running backend services , work as web server or DNS Server.
Here is the top 10 must have books for Unix and Linux , these are great books for any one working in Unix and Linux from beginner to advance users improve skills and go deeper to understand, learn, program and manage Unix and Linux systems.
Published several years ago these O’Reilly books are still useful & relevant for the current and new system administrators. Although these books may not cover latest version of operating systems yet these explains very well the underlying technical details and process which have not changed over the years.
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.