Bash Script Learnings

Monday, February 07, 2022

These are some of my notes from my time spent learning Bash script. Read and be blessed.

  1. Print statement: echo “Hello, World“
  2. Functions in bash:
  • Bash functions don’t take input parameters like functions in languages like JS, this might throw you off a bit. Instead, it saves the inputs used when calling the function and puts them in variables starting with a dollar sign and the position of the argument for instance, “$1“ -> this means it’s the first parameter supplied to the function.
// function signature (with and without an input parameter)
greeting () {
  echo "Yoo $1"
}

Assuming we call the above function like so

greeting “Chi“

The string “Yoo Chi“ will be printed on the screen.

  1. To check if an input argument exists when calling a bash script

    if [ $# -eq 0 ] <---- $# returns the number of input arguments passed to the script
      then
      else
    fi
    

$# returns the number of input arguments passed to the script.

-eq 0 evaluates if the input arguments are equal to 0.

  1. Exit status: If a command exits with 0, it is a success. If it exists, with anything other than a 0, it is a failure.
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