bash: Variable substitution - Use variable value if not-null otherwise use word.

indigowinged

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

Syntax is:
${name:-word}

if the $name variable is not-null, then substitute its value, otherwise use word

Here Brazil is set, has a value of SugarCane

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

Now make the variable Brazil null, and try again.

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