Three editors, Emacs, JOVE , and vi can be used to create files on the EECS Instructional machines. You can also create short files using the UNIX cat command.
Points to remember when editing files:
Until you are familiar with UNIX and the editor you are using, you may wish to make an extra copy of your file before you start to edit it. For example, if you want to edit a filed named mywork, you could do:
% cp mywork myworkBackUp
before doing any editing.
Editors usually create temporary files from which recovery may be possible in case of a system crash (or in case you inadvertently close the window in which you were doing the editing). However, it isn't wise to depend on recovering a file in this way. So save your file frequently during your editing session. Also, save different versions of files -- don't just save it with the same name over and over again, because if you accidentally delete huge portions of the file and wipe out your only copy, you are stuck. Consider naming files mywork.1, mywork.2, etc. Delete old copies when you are sure you have a good one.
You may need to set the terminal type so that the editor will display to your screen correctly and recognize your control characters. See Setting Your Terminal Type.
If you cannot save your file in your account for any reason (like the disk quota system won't let you), you can save your files temporarily in /tmp. /tmp is a temporary directory that all users can write into. Your files may only stay here a short time and are not guaranteed to remain there, but you can usually store files there while we resolve your disk storage problem.
JOVE is a simpler modified version of the Emacs editor. Many of the commands are similiar, but there are differences in some of the command syntax and not all Emacs commands are available in JOVE. We have tried to clarify these differences when relevent to the commands listed in this chapter.
When you use Emacs on a workstation, it creates a window for you to work in. (JOVE just runs in whatever window you start it in.) If you don't like the size or position of the window, you can change it by resizing the window.
The window is divided into two parts by a black bar containing status information. The large area above the bar is the buffer-editing area; the small area, usually a single line below the bar is the echo area or minibuffer where Emacs displays messages and prompts for responses (see Emacs/JOVE Buffers).
If you exit from Emacs normally and save your file, you will find that Emacs has also saved your original file; the filename for this old version is formed by appending a tilde (~ ) to the original filename.
Every 300 characters, Emacs saves the changes in an auto-save file. The auto-save filename is formed by adding a pound sign (#) at the beginning and end of the original filename. If you exit from Emacs abnormally, you will see this file. You can recover most of your edits from this file in case of a crash or in case you inadvertently close the Emacs window without exiting from Emacs. It isn't wise to count on this auto-save file, though; it's better to get in the habit of saving your file every five or ten minutes. You can do this without exiting from Emacs.
Since these Emacs temporary files are created automatically, you need to check your account periodically to be sure you don't accumulate temporary files and exceed your disk quota.
JOVE's behavior with temporary files is different. JOVE temporary files have names like jreca13016 and jovea13016 and get deleted when you exit JOVE normally. If you don't exit JOVE normally (due to a system crash, modem hang, etc.), you will need to delete these files manually.
You can invoke Emacs or JOVE by entering one of the UNIX commands emacs, emacs filename, jove, or jove filename. On workstations, it is more useful to invoke Emacs with the emacs & command because then you can move back and forth between your UNIX window and your Emacs window. (You cannot do "jove &" to get another window. If you want a separate JOVE window, you must open up a new window and run jove in the new window.) This allows you to enter UNIX commands without exiting from Emacs--just move the mouse cursor to the window you want to use.
In either case, be sure to save your file and exit the editor before you logoff.
In Emacs and JOVE, you are either typing text or entering commands. Commands always start with a prefix character, either the Control key CTRL or a meta key META. Press and hold down this prefix character while typing the character that completes the command.
On workstation keyboards, the Compose Character key is the Meta key. On other keyboards, it might be Edit or Alt. If you can't find your Meta key or your keyboard doesn't have one, use Esc. If you do use Esc, release it before typing the character that completes the command.
If you type a closing parenthesis, square bracket, or curly brace in the text you are entering, the cursor will momentarily move to the corresponding opening parenthesis, bracket or brace. This helps you see whether you are matching them correctly. Note that this is a mode in Emacs which can be turned off if you don't wish to use it. In JOVE, this mode is automatically on if the file you're editing has a ".c", ".l", or ".scm" extension, i.e., "homework.scm".
Table 4.1 lists commonly-used Emacs and JOVE commands.
When a command requires a response of some kind, for example a filename or a string, you will be prompted for it in the echo area at the bottom of the screen. Enter your response and press Return. When you need to enter a filename, the prompt will include the current path. If the file is in this path, just enter the filename. If it isn't, back up over the path and enter the correct path and filename.
If you change your mind in the middle of a command and wish to cancel that command, g will cancel the command you're in the middle of and return you to regular text insertion. (Sometimes you need to type g more than once for this to work.)
Table 4.1: Emacs/JOVE Commands
Topic Function Command
------- -------------------------------------- -----------------------------------
Invoke Invoke emacs % emacs &
or % emacs filename
or % emacs}
Invoke jove % jove
or % jove filename
------- -------------------------------------- -----------------------------------
Exit Exit from Emacs/JOVE CTRL-x CTRL-c
(You will be asked about saving files
except the Scratch buffer.)
------- -------------------------------------- -----------------------------------
Files Get file, open new buffer for it CTRL-x CTRL-f filename
Get file, include in current buffer
(Emacs) CTRL-x i
Get file, include in current buffer
(JOVE) CTRL-x CTRL-i
Save file CTRL-x CTRL-s
or CTRL-x s
Write to a different file CTRL-x CTRL-w filename
------- -------------------------------------- -----------------------------------
Cursor Move cursor in any direction use the arrow keys
Move forward one character CTRL-f
Move forward one word at a time META-f
Move backward one character CTRL-b
Move backward one word at a time META-b
Move down to the next line CTRL-n
Move up to the previous line CTRL-p
Move to the beginning of the line CTRL-a
Move to the beginning of the sentence META-a
Move to the end of the line CTRL-e
Move to the end of the sentence META-e
Move down one screenful CTRL-v
Move up one screenful META-v
Move to the beginning of the buffer META-<
Move to the end of the buffer META->
Move to the mouse cursor position
(Emacs only) click left mouse button
------- -------------------------------------- -----------------------------------
Delete Delete character before cursor [DELETE]
Delete character at cursor CTRL-d
Delete from cursor to end of word META-d
(with special characters)
Delete from cursor to end of line CTRL-k
with trailing return CTRL-k CTRL-k
Delete the current sentence META-k
------- -------------------------------------- -----------------------------------
Trouble Undo the last change (Emacs only) CTRL-x u
Undo the last several changes CTRL-x u ... CTRL-x u
Cancel the current command CTRL-g
Repaint the screen CTRL-L
------- -------------------------------------- -----------------------------------
Find Find next occurrence of string CTRL-s string (See Trouble in Emacs or JOVE)
and the next CTRL-s (See Trouble in Emacs or JOVE)
Find previous occurrence of string CTRL-r string
and the one before that CTRL-r
Terminate search in Emacs [ESC]
Terminate search in JOVE [RETURN]
------- -------------------------------------- -----------------------------------
Modify Change string1 to string2 from cursor
to end of buffer in Emacs META-%
Change string1 to string2 from cursor
to end of buffer in JOVE META-q
Respond to prompts with string1 [RETURN] string2 [RETURN]!
------- -------------------------------------- -----------------------------------
Move Move/copy/delete block of text.
First locate beginning of block and move cursor to start of block
Set a mark with CTRL-Space
or META-x set mark
or CTRL-@
Then locate end of block and either move cursor to end of block
Move block to kill ring, CTRL-w
or Copy it to kill ring. META-w
Finally, for move or copy, locate new
position for text block, move cursor to new position
Yank block from kill ring. CTRL-y
Replace the text just yanked with META-y
the item before it in the kill ring.
------- -------------------------------------- -----------------------------------
Buffer Display list of buffers CTRL-x CTRL-b
Switch buffers, entering name CTRL-x b buffer name [RETURN]
Move cursor to other window CTRL-x o ("oh")
Return to one window mode CTRL-x 1 ("one")
------- -------------------------------------- -----------------------------------
Help Invoke Emacs help to read tutorial CTRL-h t
Invoke Emacs help CTRL-h
Invoke JOVE help (from UNIX) teachjove
------- -------------------------------------- -----------------------------------
Recover After invoking Emacs,
ask to recover auto-save file META-x recover file
filename [RETURN]
When Emacs file is recovered, save it. CTRL-x CTRL-s
Recover JOVE auto-save file (from UNIX) jove -r
Cancel the current command CNTL-g
------- -------------------------------------- -----------------------------------
Table 4.1: Emacs/JOVE Commands
When you use Emacs or JOVE to create or modify a file, a temporary workspace called a buffer is set up for you. Your file is edited in the buffer and the original file is not modified until you ask to save the changes.
You can edit more than one buffer at a time if you wish. Some commands also create a new buffer--Emacs/JOVE will either divide your window into two parts, for example, when you ask for help, or will hide your editing buffer, replacing it with the new area. To get back to your main buffer, you need to use one of the buffer/window commands.
If you get into trouble with buffers and can't figure out what to do, enter x c to exit from the editor. You will be asked if you want to save the file you are editing (unless you are editing it in the Scratch buffer).
Online help for Emacs includes a tutorial. Look at Table 4.1.5 for how to access the online help. While you are learning Emacs and aren't familiar with moving between Emacs buffers, it is probably simpler to look at help when you are not editing a file. Then you can just exit Emacs without trying to figure out how to get back to your editing buffer.
Even if you plan to use another editor, you may want to know a little about the vi editor because it is the standard editor on UNIX systems. As do most editors, vi edits your file in a buffer and doesn't modify the original file until you ask it to.
Since vi commands are just letters like `i' and `x', you need to tell vi whether you are entering text or commands. When you enter vi, you are in Command mode, and vi assumes that everything you enter is a command. When you want to enter text, you need to enter a command to switch to Input mode. Vi then assumes that everything you enter is text until you press Escape to return to Command mode. In addition to Command and Input modes, vi also has a Line mode.
Before you invoke vi, you should know where your Esc key is. On many workstations, it is F11; on some terminals, it is labeled Esc. If you don't know where the Escape is, you can't get out of input mode and you won't be able to exit from vi normally.
You can invoke vi with vi or vi filename.
Table 4.2 lists common vi commands.
Topic Function Command
------- -------------------------------------- -----------------------------------
Before Find ESCAPE key [ESC] or [F11] or CTRL-[
------- -------------------------------------- -----------------------------------
Invoke Invoke vi to edit a file % vi filename
Invoke vi for read only % view filename
Invoke vi to recover from a crash % vi -r filename
------- -------------------------------------- -----------------------------------
Exit Exit from vi and save your file ZZ
Exit from vi and save your file :wq
Exit from vi without saving file :q!
------- -------------------------------------- -----------------------------------
Text Enter text before the cursor i text [ESC]
Enter text after the cursor a text [ESC]
Enter text at end of line A text [ESC]
Enter text on new line above cursor O text [ESC]
Enter text on new line below cursor o text [ESC]
------- -------------------------------------- -----------------------------------
Files Include another file :r filename
Save your file without exiting vi :w filename
(filename optional)
------- -------------------------------------- -----------------------------------
Cursor Move in any direction use arrow keys
Move one word at a time, forward w
Move to the beginning of the line ^
Move to the end of the line $
Move down several lines CTRL-d
Move up several lines CTRL-u
Move to beginning of buffer 1G
Move to end of buffer G
------- -------------------------------------- -----------------------------------
Delete If n in next commands is 1, omit it:
Delete n character(s) at cursor n x
Delete n words(s) at cursor n dw
Delete n line(s) at cursor n dd
------- -------------------------------------- -----------------------------------
Trouble Undo the last change u
Undo last changes on current line U
Repaint the screen CTRL-L
------- -------------------------------------- -----------------------------------
Modify Split a line at the cursor i [RETURN] [ESC]
Join two lines J
Replace one character at cursor r char
Replace several characters at cursor R chars [ESC]
Change string1 to string2 :1,\$s/string1/string2/g
------- -------------------------------------- -----------------------------------
Find Find next occurrence of string, /string [RETURN]
and the next / [RETURN]
or n
Find previous occurrence of string ?string [RETURN]
and the next ? [RETURN]
------- -------------------------------------- -----------------------------------
Move Move/copy a block of n text lines move cursor to start of block
and Remove the lines n dd
or Copy (yank) them n yy
Then locate new position for lines, move cursor to new position
and Put lines above cursor P
or Put lines below cursor p
------- -------------------------------------- -----------------------------------
UNIX Issue UNIX commando :! UNIX command
------- -------------------------------------- -----------------------------------
Table 4.2: vi Commands
Vi on many systems saves a temporary file containing your edits. If the system crashes while you are editing a file, you may be able to recover most of what you were doing, but don't count on it. Save your file frequently while you are editing. To try to recover edits from this temporary file, enter the command "vi -r filename" where the filename is the one you were editing before the crash.
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