Installing Bash

Bash can be installed on various different computer systems such as Windows and MacOS.

Something to note is that each processing system will have it’s own unique Shell with terminal commands. This makes bash scripting concepts easiy applicable to other shells with minor differences.

Git Bash Installation

to install Bash. You can do so by pressing the Link here.

Bash is a shell that is compatible with Git, which allows you to push and pull file work you have done to an online repository. More information about git can be found Here

Virtual Machine Usage**

You can also access bash through a virtual machine. This is best if you do not use a linux system.

To use a Virtual Machine, click Here

Data Types

There are a few data types that we want to be familiar with before we begin programming

  • Characters

    Characters are single letters. They are wrapped with a ” “

  • Strings

    Strings are Series of Characters that formulate words. Similar to characters, they are wrapped with a “ “ quotation in commands as they usually contain spaces and special characters that would make our code unsuable.

  • Integer

    Integers are non decimal point numbers such as 1 and 10. They are one of the smaller byte size data types. When printing and using with variables they do not require quotation marks

  • Boolean

    Boolean varaibles are those that are determined only by a TRUE or FALSE value. We can create boolean variables by assigning variables a TRUE or FALSE VAlUE.

    0 = TRUE

    non-zero = FALSE

    We can also use logical operators in Bash

    • && AND, operations that require multiple conditions to be true

      ex: a integer variable is greater then 10 AND is even

    • || OR, operations that require one condition to be true. In our example above for AND, instead of both needing to be true. One could be true and the other could be false

    • ! NOT, operations that require one condition to not be true, If we took are example above in the AND, would could say that we want an integer that is NOT even.

    We will focus more on variable assignments and computing boolean operators later

Syntax

there are two types of comments in the bash system. THe first is a single line comment


#This is a single line comment, when we run a script this will not run as code

There are also multi-line commenets


'This is a multi line 
comment, the code 
will not run
no matter how many
lines I 



Use'

Before we do anything else, it’s important to establish how we Assign Variables in bash

There are 3 types of variables we will focus on in this guide:

Local Variables

Local variables are those that only avaliable inside a function or our current shell


#These variables are easy to assign

name = "Jason"

Global Variables

  • Global Variables are avaliable for use no matte which function you are in They will require us to Specify the Path and use the Export function.
Export Path = /Usr/directory/subdirectory:$PATH

Array Variables

  • We can assign these variables multiple values, almost like a List.

Array_Variable = (1 5 10 20 30 50)

Variable Naming Conventions

  • Ensure That Your Variables are Starting With a Letter and not a function, number, or special character

  • Make your Variable Names Short, but descriptive. Keep it concise.

We can output text and other data types to our console using the Echo command. We can print various data types with this command.

If we want to print a string we can use

echo "Hello World"

We can also print out assigned Variables

Variable = "Hello World"

echo "$Variable"

The Echo command isn’t the only command we can use. We can also use printf, which is more suitable for longer strings and easily incorporate variables such as the day!

There are multiple other commands we can do to Print in Bash,


#Printf is one way that we can print a line with formatting in bash. 

'Lets Imagine its the Fourth of July in 2026.' 

printf "Todays date is $(%D,%M,%Y), happy Fourth of July!"


'this would print 

Todays date is 4, July, 2026, happy Fourth of July!

Let’s look at another example where we are only calling one variable.


name = "Elena"

printf "Hello $(name)!"

'This would print: Hello Elena!

Operators

we can use our logical operators from above in collaboration with arithmetic operators and comparison operators

Arithmetic Operators

Name Function
+ Addition
- Subtraction
* Multiplication
/ Division
% Modulo

The most foreign operator is the Modulo operator. This operator will determine the remainder for any number when it is divided by another number.


#if we were to compute 17%3. We would be left with the number 2. This is because 
the largest factor that the closest value you can achieve with 3 is 15, leaving a remainder of 2.

we can use Operators with Variables


age = 18

age next_year = age + 1

age last_year = age - 1

if we want to use a shorthand for this, we can use incremental code


age = 18 

age ++ 

#This will give us our value for age next year by adding 1

age -- 

#This will give ous an age value for the year before by subtracting 1

if we want to know our age value in three years we can use +=

age =+ 3

# We can do the opposite for 3 years ago

age -= 3

Our other set of essential operators to know how to use are Comparison Operators

Name Function
> Greater Than
< Less Than
== Equals
>= Greater than or equal to
<= Less than or equal to
!= Not equal to
gt Greater Than
lt Less Than
eq Equal to

These operators are more commonly used when we run Conditional Statements

Conditional Statements

Conditional Statements rely on using Boolean Logic to control program flow.

They will become incredibly useful when cleaning data you are working with as well as ensuring that programs run properly

our conditional statements run off of if a variable meets a certain condition.


Age=18 

#Lets run a simple if statement

if [$Age -gt 17]; then
  echo "You are an adult."
fi

We can also add a condition if our variable does not meet a certain condition using the Else statement.

if[$Age -gt 17]; then 
  echo "You are an adult.""
else
  echo"You are not an adult."
fi

If we have multiple conditions we wan’t to evalaute, we can use an Elif command.


if[$Age -lt 2];then 
  echo "you are a baby!"
elif($Age -lt 5); then
  echo "you are a toddler!"
elif($Age -lt 13); then
  echo "you are a child"
elif($Age -lt 18); then 
  echo "you are a teenager"
else
  echo "you are an adult!"
fi

Loops

Another effective way at controlling our program flow is by using Loops.

There are two loops we will be focusing on.

While loops

While loops will run a series of code until a condition has been met. When the condition has been met the code will end.


'lets make a code that prints every number from 1-100'

var = 1

while [$var -lt 100]; do 
  echo $var
  ((var++))
done

Note: Be sure your condition can be met AND that youa re Incrementing your variable.

Failing to do so can result in an Infinite Loop, which can fry your computer!

Until Loops

Until loops are similar to While loops. Except while a while loop runs until a condition becomes false. An Until loop will run until a condition becomes true


'lets run the same command' 

var = 1

until [$var -gt 100]; do 
  echo $var
  ((var++))
done

Summary

There are a wide array of functions and tools at your disposal to work with data in bash. From printing lines, to controlling the flow of programs, these introductory tools can provide you with the foundation to automate complex processes and efficiently work with files.

Next Steps

Next, this guide will focus on how to create functions and scripts in bash.

« Previous: Bash Next: Writing Functions and Scripts »