First, ensure the PerfectLib is imported in your Swift file:

import PerfectLib

You are now able to use the Env class to operate the environmental variables

• Single Variable Setting:

This statement is equal to bash command "export foo=bar"

Env.set("foo", value: "bar")

• Group Setting:

It is also possible to set a group of variables in a dictionary style:

Env.set(["foo":"bar", "koo":"kar"])
// the result is identically the same as "export foo=bar && export koo=kar"

• Single variable query:

guard let foo = Env.get("foo") else {
	// there is no such a variable
}

• Single variable query with a default value:

guard let foo = Env.get("foo", defaultValue: "bar") else {
	// there is no such a variable even with a default value??
}

• Query all system variables:

let all = Env.get()
// the result of all is a dictionary [String: String]

• Delete an environmental variable:

Env.del("foo")