README for Rterm.exe
====================

Rterm.exe can be used in three distinct modes:

1) Interactively in an MSDOS / Commands window.
2) In batch mode by redirecting its input from a file or pipe.
3) As a slave process for ESS mode in NTEmacs with flag --ess.

Its purpose is to provide something similar to the main Unix interface
for R, including a batch capability.

In interactive use the interpreter can be interrupted by Ctrl-C or
Ctrl-Break.  Input is interpreted as-is except for the keys
interpreted by getline (see below) and that special characters
can be entered by Alt+numerical-key-pad sequences of up to 3 characters,
so Alt+123 and Alt+72 give {H, for example.

Command-line editing and history in interactive use
---------------------------------------------------

Input editing handles a single line and so scrolls long lines left and
right on the same line.  Until the user presses the RETURN key they
can use Emacs-style line editing commands and can traverse the history
of lines previously typed.

Entering printable keys generally inserts new text into the buffer (unless
in overwrite mode, see below).  Other special keys can be used to modify
the text in the buffer.  In the description of the keys below, ^n means
Control-n, or holding the CONTROL key down while pressing "n".  Errors
will ring the terminal bell.

left/right, ^F/^B   : Move cursor forward/backward one character.
up/down,    ^P/^N   : Move to previous/next item on history list.
Home, ^A	: Move cursor to beginning of the line.
End,  ^E 	: Move cursor to end of the line.
ESC-F	: Move cursor forward one word.
ESC-B   : Move cursor backward one word.
^D, DEL	: Delete the character under the cursor.
^H	: Delete the character to the left of the cursor.
^K	: Kill from the cursor to the end of line.
^L	: Redraw current line.
^O	: Toggle overwrite/insert mode. Initially in insert mode. Text
	  added in overwrite mode (including yanks) overwrite
	  existing text, while insert mode does not overwrite.
^R/^S   : Perform incremental reverse/forward search for string on
	  the history list.  Typing normal characters adds to the current
	  search string and searches for a match. Typing ^R/^S marks
	  the start of a new search, and moves on to the next match.
	  Typing ^H or DEL deletes the last character from the search 
	  string, and searches from the starting location of the last search.  
	  Therefore, repeated DEL's appear to unwind to the match nearest 
	  the point at which the last ^R or ^S was typed.  If DEL is 
	  repeated until the search string is empty the search location 
	  begins from the start of the history list.  Typing ESC or 
	  any other editing character accepts the current match and 
	  loads it into the buffer, terminating the search.
^T	: Transpose the characters under and to the left of the cursor.
^U      : Deletes the entire line
^W      : Deletes the previous word
^Y	: Yank previously killed text back at current location.  Note that
	  this will overwrite or insert, depending on the current mode.
TAB	: Adds spaces to buffer to get to next TAB stop (just after 
          every 8th column).
NL, CR  : returns current buffer to the program.

