interpolate method
Substitutes $bash_vars in val
with values from env
.
Implementation
@visibleForTesting
String interpolate(String val, Map<String, String> env) =>
val.replaceAllMapped(_bashVar, (m) {
var k = m.group(2)!;
return (!_has(env, k)) ? _tryPlatformEnv(k) ?? '' : env[k] ?? '';
});