On Feb 7, 2013, at 8:27 AM, Ulrich Hertlein <u.hertlein at gmail.com> wrote: > Any particular reason why you don't just call the POSIX syscall directly, w/o exec a shell? Which is bound as Syscall.umask(): http://docs.go-mono.com/?link=M%3aMono.Unix.Native.Syscall.umask(Mono.Unix.Native.FilePermissions) - Jon