main:

	register SIGCHLD handler

	while user hasn't entered "exit" loop

		print prompt
		get command to run from user input
		trim whitespace from command

		if command is exit, quit
		else if command is sleep, then call mysleep fct
		else if command is showstatus, then print status of last command
		else call run_command fct
	end while

run_command:

	block SIGCHLD
	call parse_command fct

	call fork
	parent:
		if not bkg command, parent calls sigsuspend with empty mask, else return
	child:
		if there are no pipes
			call run_child fct
		else
			call pipe
			call fork
			parent: (will run the right hand side of the pipe)
				
				calling close and dup2 connect stdin to pipe
				call run_child fct

			child: (will run the left hand side of the pipe)


				calling close and dup2 connect stdout to pipe
				call run_child fct		

run_child:

	if input redirection is needed open input file for read, call dup2, call close
	if output redirection is needed open output file for write, call dup2, call close

	Note:  input redir on rhs of pipe is error, so is output redi on lhs of pipe

	call some version of exec (most likely execvp?)

parse_command:

	break command string into array by whitespace
	check for background command by last token being &
	check for pipe in the command, if so, break into 2 arrays at the pipe (left command, right command)
	check for input and output redirection (on both commands if pipe)

mysleep:

	use class notes to develop

sig_chld_handler:

	store exit status of command