Bash Scripting with Create a Function

Bash Scripting

 
In Linux, all tasks from execution of services to loading and unloading of modules are carried out by programs and all programs need to be executed. You use the commands to access all the basic features of kernel. Shell scripting is a way to automate such tasks, and bash is one of the language, that has capabilities enough to be called as scripting as well as a language that can be used for programming on the POSIX platform, for small tasks.  Bash Scripting else if statement

 

Create Function:

How you can create a simple function and call the function is shown in the following script. Create a file named ‘function1.sh’ and add the following code. You can call any function by name only without using any bracket in bash script. Bash Scripting with Create a Function

#!/bin/bash
function F1()
{
echo 'I like bash programming'
}
F1

Run the file with bash command.
 

 

 

Create function with Parameters:

Bash can’t declare function parameter or arguments at the time of function declaration. But you can use parameters in function by using other variable. If two values are passed at the time of function calling then $1 and $2 variable are used for reading the values. Create a file named ‘function2.sh’ and add the following code. Here, the function, ‘Rectangle_Area’ will calculate the area of a rectangle based on the parameter values.

#!/bin/bash
Rectangle_Area() {
area=$(($1 * $2))
echo "Area is : $area"
}
Rectangle_Area 10 20

Run the file with bash command.
 

 

 

 

Pass Return Value from Function:

Bash function can pass both numeric and string values. How you can pass a string value from the function is shown in the following example. Create a file named, ‘function3.sh’ and add the following code. The function, greeting() returns a string value into the variable, val which prints later by combining with other string.

#!/bin/bash
function greeting() {
str="Hello, $name"
echo $str
}
echo "Enter your name"
read name
val=$(greeting)
echo "Return value of the function is $val"

Run the file with bash command.
 

 

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