how to redirect stderr to stdout io in spawnProcess (eg stderr to stdout)?

[Timothee Cour via Digitalmars-d-learn]

How to redirect io in spawnProcess (eg stderr to stdout)?

is it safe to use it with a same File object for stderr and stdout as
follows?
Couldn't find this in the docs.

auto logFile =File(...);
auto pid = spawnShell(command,
                        std.stdio.stdin,
                        logFile,
                        logFile);