Process module:System is:module -package:lens-process

Operations for creating and interacting with sub-processes.
POSIX process support. See also the System.Cmd and System.Process modules in the process package.
A collection of FFI declarations for interfacing with Win32.
A module adapting the functions from System.Process to work with io-streams.
Use OS processes just like native Haskell functions - to generate, transform or consume streams. See Streamly.System.Command module for a higher level wrapper over this module. See also: Streamly.Internal.System.Process for unreleased functions.
Invoking external preprocessors.