Learning Linux - Create a simple shell script(Part-2)

 In part 1 of this blog series, We have seen how to work on essential Linux commands. In part 2, We will assist you to understand the basic logic and loop format while creating your first bash script. 

Prerequisites: I am hoping you have basic knowledge and experience with Linux. 

- Use scripting to automate system maintenance tasks

Scripting: #! Shebang - #!/bin/bash , # comment a line or text

- Conditional Logic(if)

IF Example: 

if [condition block] 

then

Command section

elif [condition block] 

then 

Command section

else 

Command section

fi 

    Conditional Operators

              

                

        

   

    -Processing shell command exit codes

        Exit Code: run 'echo $?' post running any command to know the exit code

    - Use Looping constructs (for, etc.) to process file, command line input

For Loop: Perform repetitive tasks 

Example: 

for mission in $(cat mission-names.txt)

do 

create-and-launch-rocket $mission

done

    while Loop usage: wait in the loop until specific condition matches/create infinite loops/Menu driven programs

Example:

while [$rocket_status = "launching"]

do

sleep 2

rocket_status = rocket-status $mission_Name

done

-> echo "Thank You :) "