bash: Variable substitution - Use word if variable name is not-null, otherwise use nothing.

indigowinged

Take into account the main readme for this section. README first.

Syntax is:
${name:+word}

if the variable $name is not-null, then substitute word otherwise use nothing.

Here Brazil is not-null, has a value of SugarCane

$ Brazil=SugarCane
$ Amazon=${Brazil:+NoDeforestation}
$ echo $Amazon
NoDeforestation

Now change Brazil to be null and try again

$ Brazil=""
$ Amazon=${Brazil:+NoDeforestation}
$ echo $Amazon

$