fflush : HasIO io => File -> io ()
Force a write of all user-space buffered data for the given `File`.
@ h the file handle to flush
pclose : HasIO io => File -> io Int
Wait for the process associated with the pipe to terminate.
@ fh the file handle to the stream to close/wait on
popen : HasIO io => String -> Mode -> io (Either FileError File)
Create a new unidirectional pipe by invoking the shell, which is passed the
given command-string using the '-c' flag, in a new process. The pipe is
opened with the given mode.
@ cmd the command to pass to the shell
@ m the mode the pipe should have