Bash Variables

To use variables in bash, you must declare them first. To do this, you can use the declare command. The following example shows how to declare a variable named my_variable and assign it the value Hello World!.

declare -x my_variable="Hello World!"

To use a variable, you can use the ${} syntax. The following example shows how to use the variable my_variable in a command.

echo ${my_variable}

You don't always need to use the ${} syntax. You can also use the $() syntax. The following example shows how to use the variable my_variable in a command.

echo $(my_variable)

Here is another example:

SOME_VAR="bla bla"
echo "The value of SOME_VAR is: $SOME_VAR"

In the previous example, the variable SOME_VAR is assigned the value bla bla. Then, the variable SOME_VAR is used in a command.