Background

Playing around with Bash and just really wrestling on how to tokenize a string and return its parts.

Honestly, it is much simpler than that.

It can only have two whole pieces; I cheated and made sure of that while curating the dataset.

Options

Here are the options available for returning data from a function

1. Use echo <data> to return the intended data
2. Use name reference

Echo Data

Outline

1. Calling Function
   • Invoke child function
     • Syntax

       • variable=$(function)

     •  Sample

       • usernameRet_=$(getUserInput)

2. Called Function
   • Return value using echo
     • Syntax

       •  echo <variable> 

     • Sample

       •  echo "$username_" 

Code

#!/bin/bash

function getUserInput()
{
	#declare variables	
	local username_=""

	#read data
	read username_

	#return variables
	echo "$username_"
    
}

#greetings
echo "hello, who am I talking to..."

#get data
usernameRet_=$(getUserInput)

echo "The name entered is $usernameRet_"

Pass by Name Reference

Outline

1. Calling Function
   • Invoke child function
     • Pass along reference
       • Notice that variable is noted without $
2. Called Function
   • Declare Variable and Set equal to the positioned argument
     • Syntax

       •  declare -n [variable]=${n} 

     • Sample

       •  declare -n usernameref_=$1 

   • In function, set a reference variable to the new value
     • Syntax

       •  [variable]=[value] 

     • Sample

       •  usernameref_="samuel" 

Code

#!/bin/bash

function getUserInput()
{

    #declare a name reference
    #The name reference should reference the first parameter
    declare -n usernameref_=$1

    #prompt user for his/her name
    echo Hello, who am I talking to?
    
    #accept name and place in name reference
    read usernameref_
    
}

# Hello World Program in Bash Shell
username=''

#invoke function
#pass variable by reference
getUserInput username

#echo data
echo "Hello $username"

Source Code Control

GitHub

Gist

Link