On this page
stderr property
final
Standard error from the process. The value used for the stderrEncoding argument to Process.run determines the type. If null was used, this value is of type List<int> otherwise it is of type String.
Implementation
final stderr;
© 2012 the Dart project authors
Licensed under the BSD 3-Clause "New" or "Revised" License.
https://api.dart.dev/stable/2.18.5/dart-io/ProcessResult/stderr.html