First Linux Bash Script – Hello World

Since we have learned basic commands in the Linux OS, we will now write our first shell script called hello.sh. You can use any editor of your choice, such as vi, gedit, nano, emacs, geany, and other similar editors. I prefer to use the vi editor:

Create a newhello.shfile as follows:

hello.sh

#!/bin/bash 
# This is comment line 
echo "Hello World" 
ls 
date 

Save the newly created file.

The #!/bin/bash line is called the shebang line. The combination of the characters # and ! is called the magic sequence. The shell uses this to call the intended shell, such as /bin/bash in this case. This should always be the first line in a shell script.

The next few lines in the shell script are self-explanatory:

• Any line starting with# will be treated as a comment line. An exception to this would be the first line with#!/bin/bash
• Theechocommand will printHello Worldon the screen
• Thelscommand will display directory content in the console
• Thedatecommand will show the current date and time

We can execute the newly created file with the following commands:

Method 1:

$ bash hello.sh

Method 2:

$ chmod +x hello.sh

By running any of the preceding commands, we are adding executable permissions to our newly created file.

$ ./hello.sh

By running the preceding command, we are executing hello.sh as the executable file. With technique one, we passed a filename as an argument to the bash shell.

The output of executing hello.sh will be as follows:

Output:

Hello Worldhello.shSun Jan 18 22:53:06 IST 2015

Since we have successfully executed our first script, we will proceed to develop a more advanced script, hello1.sh. Please create the new hello.sh script as follows:

hello.sh

#!/bin/bash
# This is the first Bash shell
# Scriptname : Hello1.sh
# Written by:  Ganesh Naik
echo "Hello $LOGNAME, Have a nice day !"
echo "You are working in directory `pwd`."
echo "You are working on a machine called `uname -o`."
echo "List of files in your directory is :"
ls      # List files in the present working directory
echo  "Bye for now $LOGNAME. The time is `date +%T`!"

The output of executing hello.sh will be as follows:

Output:

Hello student, Have a nice day !.Your are working in directory /home/student/work.You are working on a machine called GNU/Linux.List of files in your directory is :hello1.sh  hello.shBye for now student. The time is 22:59:03!