_I_n_v_o_k_e _a _S_y_s_t_e_m _C_o_m_m_a_n_d
	
	     system(command, intern=FALSE)
	
	_A_r_g_u_m_e_n_t_s:
	
	     command : the system command to be invoked, as a
	               string.
	
	      intern : a logical, indicates whether to make the out-
	               put of the command an R object.
	
	_D_e_s_c_r_i_p_t_i_o_n:
	
	     system invokes the system command specified by command.
	     If intern is TRUE then popen is used to invoke the com-
	     mand and the output collected, line by line, into an R
	     string vector which is returned as the value of system.
	     If intern is FALSE then system is used to invoke the
	     command and system returns NULL.  This function pro-
	     vides users with the ability to invoke system commands
	     on whatever platform they are using. Note that system
	     is ANSI standard, popen is not so changes may occur in
	     this function.
	
	_E_x_a_m_p_l_e_s:
	
	     # list all files in the current directory
	     # using the -F flag
	     system("ls -F")
	
	     # t1 contains a vector of strings, each one
	     # representing a separate line of output from who
	     t1 <- system("who", TRUE)