"EX" TEXT EDITOR

The text editor ex is based on, and is essentially compatible with  the
Unix  editor  ed.  Ex accepts the commands used with ed and offers many
additional features.  The most noticeable difference between  the  edi-
tors  is the feedback provided by ex: it prompts for commands by print-
ing ":" and gives useful diagnostic messages.

Many features help protect the ex user from the loss  of  work.   Under
most  circumstances,  ex's  recovery  mechanism is able to save work to
within a few lines of changes after a crash or if the phone is hung  up
accidentally.  The undo  command  can  reverse  the effects of the last
buffer-editing command, and the write command has certain checks  which
make it more  difficult to accidentally destroy files.  Users of ed can
switch to ex and benefit from these features while  continuing  to  use
the same editing commands.

Edit is the name of a version of ex which is designed for beginning and
casual users.  Type "help edit" for more information.

Documentation: The Ex Reference Manual (Version 1.1), is available from
     the  Computer Center Library, 218 Evans.  A tutorial for beginning
     users,  ``Edit: A tutorial'', can also be  obtained  there.   This
     write-up  ("help  ex") is intended to introduce users of the older
     editors to some of ex's most significant features.

Commands: Descriptions of all ex commands are given on  pages  7-15  of
     the  Ex Reference Manual.  A command may be given by typing either
     its full name (generally a word which describes its function),  or
     an  abbreviation.   All one-letter ed commands are valid abbrevia-
     tions in ex and work the same way in ex with one minor  exception:
     read (r) by default places the contents of the file read after the
     current line (.).  (The default  in  ed  is  at  the  end  of  the
     buffer.) The summaries that follow introduce a few useful commands
     that have no equivalent in ed.

help: provides information about the editor in a way  similar  to  Unix
     help.   Enter  the  editor and type "help index" for more informa-
     tion.  New topics may be added periodically.

recover: is used to recover a buffer lost in a crash or when the  phone
     is accidentally hung up. Enter the editor and use the help command
     to find out more: "help recover" and "help saferecover".

preserve: Saves the buffer as if the editor had just crashed.  Used  in
     emergencies  when a write command has resulted in an error and you
     don't know how to save your work.  After  a  preserve  you  should
     seek help.

undo (u): reverses the effects of the last command which had the poten-
     tial  of changing the buffer.  Among the commands which can be un-
     done are append (a), change (c), copy  (co),  delete  (d),  global
     (g),  move  (m),  substitute (s).  The commands edit (e) and write
     (w) cannot be undone.

z:  print segments of text (enough to fill the screen of a  crt  termi-
     nal).   By default, start with the current line, or specify a dif-
     ferent position (e.g., "1z").  Other options available;  see  page
     14 of the Ex Reference Manual.

join (j):  join lines, adjusting blank space.   By  default,  join  the
     current  line to the one after it, or specify another range (e.g.,
     "3,7j").


Open and Visual Modes: alternative modes of editing  entered  with  the
     commands   open  (o)  and  visual  (vi)  respectively.   They  are
     described on pages 16-24 of the Ex Reference Manual.   The  editor
     behaves  differently  in open and visual modes, keeping track of a
     current position in the line, as reflected by the position of  the
     cursor.  Commands are not displayed on the terminal, but their ef-
     fects on the text are shown immediately.  If  the  editor  behaves
     strangely,  you may have  accidentally entered open mode by typing
     "o".  Type a "q" to get out of open or visual mode and  back  into
     the regular editor command mode.

Options: Ex has a set of options which allow the  user  to  change  the
     editing  environment.   A  summary  of the available options is on
     page 2 of the reference manual,  and  descriptions  are  given  on
     pages  27-30.   Options are set with the command "set".  For exam-
     ple, typing "set noopen" sets an option which will not  allow  the
     user to enter open or visual mode (accidental or otherwise).  "set
     open" reverses the option.