In my previous post I've explained what Linux Shell is. Simply it is another program where you can give commands in text mode to get some work done.
However you can write a sequence of commands in a file and tell the shell to execute those commands. Then those files are called shell scripts. (File extension is .sh)
Such a script can be defined as a specific command defined to get a specific work done.
Shell scripting is very useful in a way that, if you want to do a task again and again then you can write the required commands as a shell script and execute it.
Ok, now let's try a simple shell script.
A Simple Shell Script
BASH is the default shell for Linux. Let's script using BASH commands. First we will write a simple script to print "Hello world ! " in the terminal.
You can use any text editor (gedit, vi, emacs, etc.) to write a shell script. Remember the script should be saved with .sh extension.
Write the following lines in a file and save it as 'hello.sh'.
#!/bin/bash echo "Hello, World!"
Now you can execute this hello.sh script.
It is called a shebang or a "bang" line. In this line we give the absolute path to the BASH interpreter.
Shebang includes the hash sign and an exclamation point character (#!), followed by the full path to the interpreter such as /bin/bash. This will ensure that, the script is using the specified BASH interpreter even if it is executed under another shell.
Note : Giving execution permission to the script.
To give the execution permission to the file you can use the following command.
>> chmod +x /path to file
This is a very simple shell script. We can do a lot of things using shell scripting. Hope to bring them one by one in my next posts.
- Open a terminal
- Go to the location where you've saved the above file
- Then to execute, type, sh hello.sh (Or else you can give execution permission to the above file and then execute it.)
It is called a shebang or a "bang" line. In this line we give the absolute path to the BASH interpreter.
Shebang includes the hash sign and an exclamation point character (#!), followed by the full path to the interpreter such as /bin/bash. This will ensure that, the script is using the specified BASH interpreter even if it is executed under another shell.
Note : Giving execution permission to the script.
To give the execution permission to the file you can use the following command.
>> chmod +x /path to file
This is a very simple shell script. We can do a lot of things using shell scripting. Hope to bring them one by one in my next posts.
