Variables in Bash shell scripting

What is variable ?

          Every variable contains meta data either is system defined or user defined.
      In every programming language variable play's important role,in Linux there are two types of variables System defined variable and User defined variable.

System defined variable:

         It defined by system,means every OS have some default variables called  system variables.
Example:
$PATH
$date
output
Sun May 12 11:56:34 IST 2019

User defined variable:

        It defined by user,means user need to create,define variable.
Example:
cpu=$( top -b -n1 | grep "Cpu(s)" | awk '{print $2 }'  | cut -d'.' -f1 )
here,we are taking CPU usage 



Comments

Post a Comment

Popular posts from this blog

Awk command with simple examples

Image
Now, we are going to learn very interesting and Most important  in  Linux Why late lets know about Awk command,one of the mostly used command in scripting. awk command used to manipulate data | using this AWK command we can generate specified reports as per our requirement. Syntax : awk ‘BEGIN {start_action} {action} END {stop_action}’ filename let me explain about awk command with simple examples Example 1: How to print entire   data of the file cat filename | awk '{print}' cat filename | awk '{print$0}' both " awk '{print}' and  awk '{print$0}'  " used to print entire date Example 2: How to print  very first column cat filename|  awk '{print$1}' awk '{print$1}'  used to print very first column   awk '{print$1}'   used to print second column   Example 3: How to print p attern Matching Technique in Awk. free -m | awk '{/Mem/print}' here, we are matching Mem using  awk '{/Mem/p...
Read more

Learn Linux in Telugu | Linux complete Free Course in Telugu by 7Hills

               Hello, Here we are going to learn complete Linux course freely & Simply way. Why Linux?                   Linux is an heart the operating system,   Based on the Linux Kernel their are different types of Linux flavors available i.e.. RedHat, Centos, Fedora, Mint Debian, Kali, OpenSUSE...etc Features of Linux Open source. Multi-user. Multitasking. Hierarchical file system. Portable. Wide hardware support. No need to worry, we explained each and every topic clearly just click on the below links for watch on Youtube.   1.       Linux outline in Telugu 2.       Linux introduction In Telugu 3.       Linux architecture In Telugu 4.       Linux Directory Structure In Telugu 5.       Linux Basic Commands In Telugu 6.    ...
Read more

rsync Command Examples | rsync Command In Telugu

Image
Hey! Well come back! Here, we are going to learn very useful command rsync. basically rsync is used to sync file system with same structure. It also used to data backup/copy. rsync is free command line utility & In most of the system it available defiantly. We can install rsync utility in debian based system using below command apt-get install rsync We can install rsync utility in redhat based system using below command yum install rsync Below command used to copy files without using option rsync /root/Desktop/original/* /root/Desktop/backup/ Below command used for recursive copy, it means with sub folders. rsync -avhr /root/Desktop/original/* /root/Desktop/backup/ Here     -a is used for archive data.     -v is used for show output.     -h is used for show copied data in MB's,it means human              readable  format. Below command used for include or exclude  rsync -avz --include ...
Read more