Using functions and positional parameters

Similar to other programming languages, function is a way to write a set of actions once and use it multiple times. It makes the code modular and reusable.

The syntax of writing a function is as follows:

function function_name
 {
  # Common set of action to be done
 }

Here, function is a keyword to specify a function and function_name is the name of the function; we can also define a function in the following ways:

function_name()
{
  # Common set of action to be done
}

The actions written within curly braces are executed whenever a particular function is invoked.

Calling a function in bash

Consider the following shell script that defines the my_func()function:

#!/bin/bash
# Filename: function_call.sh
# Description: Shows how function is defined and called in bash

# Defining my_func function
my_func()
{
  echo "Function my_func is called"
  return 3
}

my_func # Calling my_func function
return_value=$?
echo "Return value of function = $return_value...