.(["env" : getenv() + (["TERM":"vt100"])
args is per default no argument(s),
env is reset to the given mapping, or kept if the argument is 0. fds is your stdin, stdout and stderr. Default is local pipes (see stdin et al). fds_to_close is file descriptors that are closed in the forked branch when the program is executed (ie, the other end of the pipes).