Scripting Classroomnotes 03/Feb/2023

Shell Scripting Contd

• Scripting is a list of commands that are executed in a particular order.
• Generally the script executes the commands in the order they are written, but we can also specify
  • instructions to repeat the same command multiple times (loops)
  • to skip some commands based on some conditions (conditionals)
• Sample script

#!/bin/bash
echo 1
echo 2
echo 3
echo 4
echo 5

• Execute this script hello.sh
  
• Consider the following activities
  • Create a directory under /opt/backup folder that has today’s date in the name eg /opt/backup/qtdevops-03022023
  • Copy all the files from /home/qtdevops/ into this directory
• Solution:
  • Find a command to get the date and then data in some format.
  • Refer Here for the script added

Variables

• Variables will store the value and we can use the values further in the script
• Types of Variables:
  • Environmental Variables:
    • The shell maintains environmetal variables which are common to applications/scripts across the current session
      
    • To use the environmental variable $<ENV-VAR-NAME>
    • To set environmental variables you can use export command
      
  • User Variables:
    • These are the variables set in a shell script
    • Refer Here for the usage of user variables

Exercise

• Findout all the environmental and user variables in the Refer Here