How to write hello world bash shell script

The procedure is as follows:

1. Create a new file called hello.sh using a text editor such as nano or vi:
   nano hello.sh
2. Add the following code:
   #!/bin/bash
   echo "Hello World"
3. Set the script executable permission by running chmod command:
   chmod +x hello.sh
4. Run or execute the script using following syntax:
   ./hello.sh
   OR
   sh hello.sh
   OR
   bash hello.sh

Sample session:

Improving Hello World script

Let us create a program called update-hello.sh as follows:

#!/bin/bash
# Usage: Hello World Bash Shell Script Using Variables
# Author: Vivek Gite
# -------------------------------------------------
 
# Define bash shell variable called var 
# Avoid spaces around the assignment operator (=)
var="Hello World"
 
# print it 
echo "$var"
 
# Another way of printing it
printf "%s\n" "$var"

Run it as follows:
chmod +x update-hello.sh
./update-hello.sh
Where,

• First line of the script (#!/bin/bash) is shebang. It tells the Linux/Unix how to run the script.
• Each shell comments start with #.
• Declaring a variable: Variable_Name="Values_here".

Next create a program named hello2.sh to display current date and computer name as follows:

#!/bin/bash
var="Hello World"
 
# Run date and hostname command and store output to shell variables
now="$(date)"
computer_name="$(hostname)"
 
#
# print it or use the variable
# Variable names are case sensitive $now and $NOW are different names
#
echo "$var"
echo "Current date and time : $now"
echo "Computer name : $computer_name"

Run it as follows:
chmod +x hello2.sh
./hello2.sh

Reading a value from input

Our final hello world program reads input from the keyboard using the read command. Create a bash shell script named hello-input.sh:
$ nano hello-input.sh
Append the following code:

#!/bin/bash
# Clear the screen
clear
 
# Read input using read command
read -p "May I know your name please? " name
echo "Hello $name, let us be friends"
echo ""

Save and close the file. Run it as follows:
$ chmod +x hello-input.sh
$ ./hello-input.sh

Running your shell script in “debug” mode

Pass the -x and -v option:
bash -x hello-input.sh
bash -v hello-input.sh
bash -x -v hello-input.sh
For more info see Linux Shell Scripting Tutorial and bash command man page:
man bash
help read