A bash script is just a text file with commands in it. Command like the ones we can give on the command line. It does not have to have any particular extension, but often people use the .sh extension. For example foobar.sh In order to be able to run it we need to make it executable chmod u+x foobar.sh or to make it exacutable for all the users on the system use chmod +x foobar.sh. To ensure the script always executes as a bash script, and not as the "current shell of the user" we need to add ad a sh-bang line.

#!/bin/bash
examples/script/hello_world.sh
echo Hello
echo World

$ ./examples/script/hello_world.sh 
Hello
World
examples/script/hello_world_more.sh
echo Hello World
$ ./examples/script/hello_world_more.sh 
Hello World
examples/script/hello_world_n.sh
echo -n Hello
echo World

$ ./examples/script/hello_world_n.sh 
HelloWorld
examples/script/hello_world_space.sh
echo -n "Hello "
echo World

$ ./examples/script/hello_world_space.sh 
Hello World