The C Users' Group Library 1994 August

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RED A Full Screen Text Editor Version 7.0 January 26, 1990 Written by Edward K. Ream 1617 Monroe Street Madison, WI 53711 CHAPTER 1 BEFORE USING RED This chapter provides information you should know before using RED. It lists the hardware and software required, it reminds you to create a backup copy of the distribution disk containing RED, and it lists the files that are distributed with the RED system. System Requirements o An IBM PC/XT/AT computer or compatible with two floppy disks or a hard disk. o The MS-DOS operating system. o Either the Microsoft C compiler or the Turbo C compiler. Minor modifications in RED's source code will allow RED to compile using other C compilers. Backing Up Your Disks Please back up the distribution disks before using RED. Use the DOS COPY command to copy all the files on the distribution disks to backup disks. Your backup disks will be used as working disks. The following files appear on your distribution disks. File Description read.me Please read this file first. redman.doc This file. redtech.doc Technical notes. red*.h Header files for RED. red*.c Source code files for RED. red.exe Executable version of RED. red.mak Turboc C make file for red.exe. red.lnk Turboc C link file for red.exe. mred.mmk Microsoft C make files for red.exe. mred.ml Microsoft C link files for red.exe. sherlock.doc Documentation for the Sherlockt debugging system. dummysl.h Null definitions for all Sherlock macros. reddb.exe Executable version of RED, with Sherlock macros added. red.mak Turboc C make file for reddb.exe. red.lnk Turboc C Link file for reddb.exe. mred.mmk Microsoft C make file for reddb.exe. mred.ml Microsoft C link file for reddb.exe. CHAPTER 2: REFERENCE GUIDE This chapter tells you how to use REDDit describes RED's commands and functions, tells you how to use them and explains what to do about warning messages. Each section discusses a particular activity or task that you do while creating, changing or saving a document. Starting RED When RED starts up it does the following: o Clears the screen and prints a welcoming message. This signon message tells you what version of RED you are using and how to print help messages. Help messages are simply reminders of what you can do with RED. o Draws the prompt line at the top of the screen. For now, just notice this top line; we'll discuss the information on it in a moment. o Puts the cursor just below the prompt line. The cursor is a distinctive character on the screen. (On most video terminals the cursor is shown as a box or underline which blinks.) o Draws the end-of-file marker or the third line of the screen. This line looks like: ----------------------------- End of file. ------------------------------------ Initially, most of the screen is blank because RED's buffer or internal memory doesn't contain any information. You can think of the screen as a window into part of this buffer. As you make additions, corrections and deletions to the buffer, those changes appear automatically on the screen. The purpose of the end-of-file marker is to make absolutely clear what the buffer does and does not contain. Let's look again at the prompt line. At the far left, you will see that the line says, line: 1 column: 0 These two fields indicate which lines in the buffer and column on the screen that the cursor is on. The next field says, ..no file.. indicating that the buffer does not contain any information from a file. Finally, the prompt line tells you what mode RED is in--either edit mode, insert mode or overtype modes. In most respects, RED works exactly the same regardless of mode; that makes RED simple to use. However, some details on how RED works change depending on mode; that makes RED powerful. We'll see later that not only can you make RED change modes easily, but you can have RED change modes automatically if you so desire. This feature allows you to make RED work exactly the way you want. We'll discuss modes shortly in complete detail. For the moment, just notice what mode RED is now in. At your option, you have have RED automatically load a text file into RED's internal memory (the buffer) when RED initially starts up. For example, if you had invoked RED as follows: red document.txt then RED would have loaded the file document.txt into the buffer already. In that case the screen would not be blank but instead would show you the first several lines in the file and the prompt line would be "document.txt" instead of "..no file.." Using Function and Control Keys The term function key refers to a key on your keyboard that does one and only one action or function. Just about everything you do with RED involves using function keys---they are used to change modes, to insert or delete lines and characters, to move the cursor, to split and join lines and to start commands. There is also a "repeat" function key that repeats the previous function. All function keys can be used in insert, overtype and edit modes and all function keys do the same thing, regardless of the current mode. RED needs to be able to distinguish function keys from what you are typing into the buffer. Thus, function keys must be assigned to control keys on your keyboard. A control key is typed by holding down the key marked CTRL on your keyboard while typing another key. For example, you type the "control c key" (abbreviated control-c) by typing the letter c while holding down the CTRL key. Throughout this chapter, the name of each function key is followed in parenthesis by the control key assigned to it by default. For example, this chapter refers to the split function key as split (control-s). So in order to press the split function key you must actually press the control-s key on your keyboard. Changing Modes RED has three modes: edit mode, insert mode and overtype mode and all function keys act the same regardless of modeDthe only difference between the three modes is what happens when you type a non-control character. You use three different keys to switch RED between modes--the enter iNsert (control-n), the enter overType (control-t) and enter edit (control-e) function keys. Besides these three keys which explicitly change from one mode to another, RED can change from one mode to another automatically in three situations: 1) after every command, 2) after inserting new lines and 3) whenever the cursor moves up or down one line. You can change how RED switches modes using three sets of commands: def0edit, def0ins, def0over, def1edit, def1ins, def1over, def2edit, def2ins, and def2over. (We haven't discussed commands yet, so if you are reading this for the first time just realize that how RED switches between modes isn't carved in stone.) I prefer to use a hybrid combination of edit mode and insert modeDI configure RED so it acts as if I had issued def0edit, def1ins and def2edit commands. For example, to make RED into an "overtype mode editor" just issue the def0over, def1over and def2over commands. You'll never see insert or edit modes again unless you switch to them explicitly. Inserting Characters with Insert and Overtype Modes In this section we'll look at insert and overtype modes, leaving edit mode for much later. Let's discuss insert mode first, so if RED is not already in insert mode press the enter insert (control-n) function key. Notice that the prompt line indicates that the mode has changed. In insert mode, any plain (i.e., non-control) character you type is inserted into the buffer without replacing any other information. Characters to the right of the cursor "move over" to allow room for the new character. To jump the gun a bit, you can make the cursor move left without erasing anything by hitting the left (control-l) function key. Try the following: insert a few characters, move the cursor left once or twice and insert some more characters. Overtype mode works just like insert mode except that a character directly under the cursor is replaced by what you type, instead of moving to the right. In other words, in overtype mode you "type over" whatever is already on the line. Compare overtype mode to insert mode: enter overtype mode, type some characters, move the cursor to the left and type some more characters. Inserting New Lines You can't edit much if you are confined to a single line. You end one line and begin another using the insert down (carriage return or control-m) function key. Try it. The insert up (line feed or control-j or insert) function key is a companion key to the insert down key. The insert up key inserts a blank line above the current line. The insert up (line feed or control-j or insert) and insert down (carriage return) function keys may also cause RED to shift automatically to a different mode. Which mode RED shifts to after hitting these keys may be changed at any time using the def1edit, def1ins and def1over commands. For example, the def1edit command causes RED to shift automatically to edit mode whenever the insert down or insert up function key is pressed. Notice that RED will split the line automatically if the cursor reaches the end of screen while you are inserting characters. This feature is called line wrapping. Try it out. Notice also that line wrapping never happens if there are characters to the right of the cursor. Moving the Cursor In order to change your text, you must position the cursor near the next to be changed. This section tells you how to do that. The right (control-r) and left (control-l) function keys move the cursor right or left one column. However, these keys always leave the cursor on the same line. For example, nothing happens if you hit the left key when the cursor is at the leftmost column of the screen. The up (control-u) and down (control-d) function keys move the cursor up and down one line respectively. The cursor will not move above the first line or below the last line of the file. The up (control-u) and down (control-d) function keys may also cause RED to shift into a different mode. Which mode RED will shift to may be changed at any time using the def2edit, def2ins and def2over commands. For example, the def2ins command causes RED to shift to insert mode whenever the up (control-u) or down (control-d) function key is pressed. The page up (control-q or page up) and page down (control-p or page down) function keys move the cursor up or down one page of the file. You need not wait for the screen to be completely redrawn before hitting another character. The scroll up (control-w) and scroll down (control-o) function keys scroll the cursor up or down. Hitting any key interrupts the scrolling. The home (home) key positions the cursor at the start of the top line of the screen and the end (end) key positions the cursor at the start of the last line of the screen. The word forward (control-f) and word backward (control-b) function keys move the cursor forward or backward one word. A word is any sequence of characters separated by end-of-line, blank or tabs. Deleting Characters and Lines A large part of my writing involves deleting characters and lines: two words forward and one word (taken) back--two sentences written and one erased. RED lets you do this without any fuss. To delete a single character you must first position the cursor either directly over the character or just to its right. The delete left (control-h or backspace) function key deletes the character to the left of the cursor. Nothing happens if the cursor is up against the left edge of the screen. The delete under (del) function key deletes the character directly under the cursor. Use the delete line (control-z) function key to delete the entire line on which the cursor rests. The screen is redrawn with the line squeezed out. Undoing Mistakes Sometimes RED lets us work faster than our thoughts--or maybe our fingers have a mind of their own. In any case, there is occasionally a need for undoing the "improvements" that have just been visited upon a line. The undo (control-x) function key restores a line to what it was when the cursor last moved to the line. In other words, the undo function undoes whatever editing or inserting you have done on the current line. Several words of warning: you cannot use the undo (control-x) function key to restore a line that has been erased with the erase line (control-z) function key. Also, you cannot use the undo (control-x) function key to undo a change once you have moved the cursor to another line. Splitting and Joining Lines Being able to split a line into two pieces or make one line from two is often very handy. For instance, to edit a line longer than will fit on the screen, you would first split the line, then make your corrections and finally glue the line back together again. The split (control-s) function key splits the current line into two pieces. Everything to the left of the cursor stays right where it is. All other characters are moved to a new blank line crated below the original line. The split (control-s) function key acts just like the insert down (carriage return) function key if the cursor is positioned at the right end of the line. The glue (control-g) function key combines two lines into one. This key appends the current line to the line above it and then deletes the lower line. The new line is allowed to be longer than the width of the screen. Inserting Control Characters In rare cases, it is desirable to insert control characters into the buffer. This requires a special function key. The verbatim (control-v) function key enters the next key pressed into the buffer, no matter what it is. For example, to insert a control-s into a buffer, type control-v control-s. After you press the verbatim (control-v) function key, but before you press the second key, the prompt line says 'verbatim'. Repeating the Previous Function The repeat (control-a) function key repeats the last function key, edit mode function or escape sequence. For example, typing control-p control-a is the same as typing control-p twice. As we will see, using the repeat key can sometimes save you typing. The repeat key "amplifies" the effect of several functions as shown in this table: original function amplified function begin line home end line end page home page up end page page down For example, typing ESC b ^a ^a is the same as typing ESC b ESC h ^q because the first ^a amplifies the begin line function (^b) into the home function (ESC h) and the second ^a amplifies the home function into the page up function (^q). Using Commands Up until now, we have been talking about functions, i.e., operations that are done by pressing a single function key. However, functions are not appropriate in all situations--they might require additional information or they might potentially alter too much work to be safe. Commands are RED's way of performing complex or dangerous operations quickly and safely. You start each command with the enter command (control-c) function key. Try this key out now. Notice that the cursor moves to the prompt line. All commands end with a carriage return, and if you type nothing but a carriage return the command is terminated. You can also exit from a command by hitting either the enter edit (control-e), the enter insert (control-n) or the enter overtype (control-o) function key. OK, exit the command in one of the ways just mentioned. If you make a mistake while entering a command, just hit control-h (also known as backspace) to erase single characters. You may use either upper or lower case for commands. At any time, you may change which mode RED will shift to by using the def0edit, def0ins and def0over commands. For example, the def0over command causes RED to shift to overtype mode after each command. Creating, Saving and Loading Files After you have finished working on your document you must save it on a file. This is a two-step process: you must name the file and you must actually save your work to that file. Use the name command to name your file. Just type "name" (you don't type the double quotes) followed by the name you want your file to have, followed (as always) by a carriage return. Notice that the prompt line changes to reflect the new file name. Aside: Your file name can haven o more than eight letters or digits, followed optionally by a period and no more than three more letters. The question mark (?) or star (*) are not allowed in file names. Examples: legal names illegal names abc ???.abc foo.bar foo.* letter.doc letter.doc1 12345678.doc 123456789.doc xy.z x.y.z The last step in creating a new file is writing your work to the file. If you don't do this your work will be lost, but don't worry, RED reminds you if you haven't done so when you try to leave. To save your work, use the save command. While the save command is in progress, the message "--saving--" appears on the prompt line. The save command doesn't take any arguments; your work is saved to the file named on the prompt line. If you issue the save command when the prompt line indicates "..no file.." RED complains saying, "file not named". Hit any key to clear this message and continue. If RED says "file exists' instead of "--saving--" it means that a file already exists on the disk with the name shown on the prompt line. You now have two choices: you can pick another name for your file and do the save command over again or you can use the resave command to replace what is already on that file with your present work. (Watch out: the resave command destroys the previous contents of the file.) If you use the resave command and the file does not already exist, RED gives you the "file not found" message. As with the save command, the resave command never takes any arguments. As mentioned earlier, you can load an already existing file (say memo) at the same time you start RED by typing 'red memo'. If RED finds the file on the disk, RED loads that file and updates the prompt line to indicate the name of the file. This is the file name used by the save and resave commands. (of course, you can use the name command at any time to change this name.) If the file is not found the prompt line says "file not found". As always, hit a carriage return to clear this warning message. If you did not give a file name when you started RED, or if you got the "file not found" message, you can use the load command to load a file into the buffer. The load command takes one argument--the name of the file to be loaded. As you would expect, the load command changes the file name on the prompt line so that the save and resave commands will update the file you just loaded. Purely as a convenience, RED treats the red command just like the load command. Examples: load abc.doc red memo save resave Unlike some other editors, RED's load command does not create a file if it does not exist, so you haven't created any unwanted file if you don't get the name right. Neither does the load command change the file name on the prompt line if the file does not exist. This feature makes the save and resave commands safe to use in almost all circumstances. The load command replaces whatever is in the buffer by the contents of the file being loaded. For your protection, the load command asks "Buffer not saved, proceed?" if loading the file might destroy unsaved work. If you answer 'y' the load operation begins and whatever is in the buffer is lost. Otherwise, the load command terminates and you have an opportunity to save your work. Leaving RED There are two ways to leave RED. The first is the exit command, which takes no arguments. For your protection, RED asks "Buffer not saved, proceed?" if you issue this command before you have saved your work. Type 'y' to exit anyway or type anything else to cancel the command. The quit command may or may not be available with your version or RED. If it is available, the quit command works like the exit command (it takes no arguments), except that RED saves information on your disk so RED can reload the file you were working on quickly and automatically. When RED is next restarted, it looks for this information to resume editing right were you left off. The quit command is nice to have if you do a lot of work with a single file because it saves 99% of the time it takes to load a file with the load command. However, the quit command does have some drawbacks. First, the saved information (the work file) takes up space on the disk when RED is not being used. Second, if the work file is erased, some of your work may be lost. Third, if you interrupt RED by hitting your computer's reset key, the work file will not have the proper file status line. The next time you start RED, RED will complain and you should erase the work file by hand. Searching for Patterns As your file becomes longer and longer, it becomes harder and harder to find the parts of it that you want to change. Instead of searching for words or phrases yourself, RED can do the searching for you. In order to do searching, you must specify patterns which tell RED what to look for. A pattern is simply any string of characters ended by a carriage return. Most letters in patterns just stand for themselves: Examples: o The pattern 'abc' matches the three letters 'a' 'b' and 'c' o The pattern '12-4' matches the four characters '1' '2' '-' and '4' There are three characters which have special meanings within patterns and make patterns more powerful. A question mark in a pattern matches any character at all. Examples: o The pattern '?bc' matches any 'bc' that is not the first character on a line. o The pattern 'a?c' matches an 'a' and 'c' with exactly one character between them. o The pattern '???' matches any three characters on the same line. A leading caret ('^'), i.e., a caret that appears at the start of a pattern, matches the start of a line. Examples: o The pattern '^abc' matches any line that starts with 'abc'. o The pattern '^??abc' matches any line with 'abc' starting in column 3. A caret that does not start a pattern loses its special meaning. Examples: o The pattern '^?^a' matches any line with a '^' in column 2 followed by an 'a'. o The pattern '?^' matches any '^' which is not in column 1. A trailing dollar sign, i.e., a dollar sign that appears at the end of a pattern, matches the end of a line. Examples: o The pattern 'abc$' matches any line that ends with 'abc'. o The pattern 'abc??$' matches any line with exactly two characters after 'abc'> A dollar sign that does not conclude a pattern loses its special meaning. Example: o The pattern '^?$?' matches any line with '$' in column 2 followed by some other character. A leading caret and trailing dollar sign may be used in the same pattern. Examples: o The pattern '^abc$' matches any line that contains only 'abc'. o The pattern '^?$' matches any line with exactly one character. The find command puts the cursor at the start of the pattern when the pattern is found. You invoke the find command as you would expect: type the enter command (control-c) function key followed by find <CR>. The prompt line will now ask you for a search mask. This means that you should enter a pattern to search for. Type in the pattern and end it with a carriage return. The find command will now search from the place where the cursor is, looking for the pattern. If the find command reaches the end of the buffer without finding a match the search "wraps around the buffer," i.e., the search continues form the start of the buffer to the line where the search originally commenced. If the find command eventually matches the pattern, RED will place the cursor at the start of the pattern. If no match is found, RED will simply put the cursor back where it was before the find command was invoked. The findr command works just like the find command except that it searches backwards through the buffer for a pattern. The search command searches for a pattern just like the find command, but the search may be continued after a pattern is found. When a match is found, the prompt line will say, "next, exit?". If you hit an 'n', the search will continue. The search will end if you hit any other key. The change command searches for a pattern in a manner similar to the search command, but when a match is found a substitution is made. When you invoke the change command, you will be asked for a search mask, just as with the search command. Next, you will be asked for a change mask. Whenever the pattern specified by the search mask is found, the pattern specified by the change mask is substituted. Carets and dollar signs have no special significance in a change mask. Question marks in a change mask are replaced by the character that matched the corresponding question mark in the search mask. For example, suppose the search mask is 'a?b?' and the change mask is 'A??C'. If the characters that match the search mask are 'a+b-' would be replaced by 'A+-C' because the two question marks in the change mask would be replaced by '+' and '-' respectively. The change command does not make all changes in the buffer at once. When a match the substitution is made on the screen and the prompt line asks, "yes, no, all, exit?" The substitution is undone if you reply 'n' or 'e' and the change command terminates if you say'e'. If you reply 'y', the change is made and the searching continues. If you say 'a', the change is made and searching continues. However, when you say 'a', all changes are made without further prompting and no further changes are shown on the screen. Only the line number field on the prompt line shows that changes are being made. The find and findr commands start searching from the current line, but you can change that by invoking these commands with a line number. Examples: command search starts at find current line find 1 line 1 findr 9999 end of buffer The change and search commands look through the entire buffer for the pattern unless you specify a portion of the buffer to search. Examples: command what is searched search every line search 1 9999 every line change 70 90 lines 70--90 search 50 lines 50--end change 90 9999 lines 90--end Moving Blocks of Lines One of the most common editing operations is cutting and pasting. RED has four commands that make this easy. The move command moves a block of lines from one place in the buffer to another. The move command takes three arguments, the first line to move, the last line to move, and the line after which the lines are to be moved. Only one line is moved if only two line numbers are given. Examples: command line(s) moved where moved move 1 2 3 1--2 after line 1 move 1 2 0 1--2 before line 1 move 2 10 2 after line 10 The copy command works just line the move command except that a copy of the lines is moved so that the original lines stay where they were. Examples: command line(s) copied where copied copy 1 2 3 1--3 after line 3 copy 1 2 0 1--2 before line 1 copy 1 8 2 after line 8 The extract command copies a block of lines to a file without erasing the block from the buffer. Take care with this command: the file is erased if it already exists. Another caution: integers are legal file names, so make sure you include the file name. Examples: command file name lines written extract abc abc whole file extract 1 2 1 line 2 extract abc 1 2 abc lines 1--2 extract f 1 999 f whole file The inject command is the companion to the extract command. The inject command adds a file to the buffer. It does not replace the buffer as does the load command. Examples: command where injected inject abc after current line inject abc 0 before line 1 inject abc 9999 at end of file inject abc 50 after line 50 You can use the extract and inject commands to cut and paste between different files. Extract a block of lines from the first file into a temporary file, load the second file and then inject the lines from the temporary file into the second file. Setting Tab Stops Tab stops effect how tabs are shown on the screen and printed on the printer. RED sets tab stops every 8 columns to begin with, but this can be changed with the tabs command. After this command the screen is redrawn so you can see the results of the new tab setting. Examples: command width of tabs tabs 8 tabs 8 8 tabs 4 4 Enabling and Disabling Line Wrapping Initially, line wrapping is enabled. Lines are split whenever a) the cursor is the last character of the line and b) the cursor is at the right edge of the screen and c) a character is inserted. The nowrap command disables line wrapping. When line wrapping is disabled, no further insertions are allowed in a line when the cursor reaches the right margin of the screen. If you want to enable line wrapping again after using the nowrap command, use the wrap command. Listing the Buffer The list command prints the buffer on your printer. Lines are formatted just as they are on the screen, but the length of the print line, not the width of the screen, determines where long lines are truncated. You can interrupt the listing at any time by hitting any control key. Examples: command what is listed list the current line list 15 line 15 list 1 9999 the entire buffer list 400 500 lines 400--500 Deleting Multiple Lines The clear command erases the whole buffer, while the delete command deletes one or more lines. The clear command will caution you if erasing the buffer might cause work to be lost, but the delete command does not, so be careful. Examples: command what is deleted clear the whole file delete 1 9999 the whole file delete the current line delete 25 line 25 Choosing How RED Switches Modes As mentioned before, RED will automatically switch from one mode to another in three situations: 1) after every command 2) after inserting new lines and 3) whenever the cursor moves up or down one line. You can choose exactly what RED will do in each case. This section tells how. The def0edit, def0ins and def0over commands determine which mode (edit, insert or overtype) RED will be in after each command. For example, after the def0edit command is given, RED will switch to edit mode after each command. The def1edit, def1ins and def1over commands determine which mode RED will be in after the insert up (line feed) or insert down (carriage return) function keys are pressed. For example, after the def1ins command is given, RED will switch to insert mode whenever a new blank line is created. The def2edit, def2ins and def2over commands determine which mode RED will be in after the up (control-u) or down (control-d) function keys are pressed. For example, after the def2over command is given, RED will switch to overtype mode whenever the up or down function keys are pressed. Edit Mode Functions and Escape Sequences Edit mode lets you avoid typing so many control keys. In edit mode, typing regular (i.e., non-control) keys makes RED act as though function keys were pressed. Some people find using normal characters in this way confusing, which is why this section has been left until now. Other people, myself for instance, think that edit mode is a great convenience. Escape sequences are an added frill; they are a way of executing edit mode functions without switching to edit mode. Escape sequences consist of the escape (ESC) function key followed by an edit mode function. For example, the 'h' edit mode function homes the cursor to the top left corner of the screen. If RED were in insert mode I could home the cursor using the ESC h escape sequence without having to switch RED to edit mode first. By the way, edit mode commands and escape sequences may be typed either in upper case or in lower case. Here is a list of the edit mode functions. For simplicity's sake the functions are listed in alphabetical order. Again, each function may be used outside of edit mode by using an escape sequence. The space bar moves the cursor right one column. Nothing happens if the cursor is up against the right edge of the screen. In other words, the space bar works exactly the same as the right (control-r) function key. The '+' key moves the cursor down a half a page. The '-' key moves the cursor up a half page. The b key puts the cursor at the beginning (left hand edge) of the line. This key is amplified by the repeat key into the home function. For example, typing b ^a in edit mode is the same as typing b p. Similarly, typing ESC b ^a in insert mode is the same as typing ESC b ESC p. The d key causes the cursor to move down rapidly. Type any key to stop the scrolling. The e key moves the cursor to the right end of the line. This key is amplified by the repeat key into the end page function. For example, typing e ^a in edit mode does the same thing as typing e q. Similarly, typing ESC e ^a is the same as typing ESC e ESC z. The g key moves the cursor to another line. After you type the g the cursor will move to the prompt line. The prompt line will show 'goto:' Now type a line number followed by a carriage return. By the way, there is a g command that works the same way. The h key homes the cursor to the top left corner of the screen. This key is amplified by the repeat key into the page up function. Thus, typing h ^a in edit mode is the same as typing h q. Similarly, typing ESC h ^a works the same as typing ESC h ESC q. The k key deletes all characters from the cursor up to but not including the word that starts with a "search character". Everything from the cursor to the end of the line is deleted if no word starts with the search character. After you hit the k the prompt line displays 'kill'. Now type the search character. If you wish to cancel the k command before specifying the search character, press any control character. The k command will be stopped and no deletion will be made. If too much text is deleted, use the undo key and try again. Example: Typing k <space> deletes the following word. The m key moves the cursor to the start of the line in the middle of the screen. The p key moves the cursor down one page. You don't have to wait for the screen to be completely redrawn before you hit another key. Thus, hitting several p keys is a very fast way to move short distances. The q key is the companion to the p key. It moves the cursor up one page. The s key moves the cursor to the next word that starts with a search character. If no word starts with a search character. If no word starts with the search character the cursor is moved to the end of the current line. After you hit the s key, the prompt line displays 'search'. Now type the search character. Example: Typing s <space> moves the cursor right one word. The u key moves the cursor up rapidly. You stop the scrolling by typing any key. The x key replaces the character under the cursor. After you type the x command the prompt line displays 'eXchange'. Now type the new character. If you hit a control character no change is made and the x command is canceled. The z key moves the cursor to the start of the last line on the screen. This key is amplified by the repeat key into the screen down function. For example, typing z ^a in edit mode is the same as typing z p. Similarly, typing ESC z ^a is the same as typing ESC z ESC p. What To Do About Error Messages RED will print a message on the prompt line should anything go amiss. You clear the message by hitting any key. Usually the message will be a reminder about how to enter a command. For example, if you forget how to use the move command, just do the move command anyway. RED will say, usage: move <block> <n> This may jog your memory enough so you won't have to look up the command in this chapter. The only serious error you might see is: write error: disk or directory full?? This error usually means that RED could not complete a save or resave command because there was not enough room on the disk. This error is not too serious; you should be able to recover from this error if you do a save or resave to another disk. But you should never remove the disk from which you invoked RED! (That disk contains the work file, which is what you are trying to save.) More rarely you can see this error when you are making insertions into the buffer. When this happens, try to save the buffer to a new file on another disk. Once again, do not remove the disk from which you invoked RED! This may or may not work, depending on whether another disk is available Thus, you may lose the work you have done since your last save or resave. Obviously this is not a pleasant occurrence. You can avoid this problem by making sure that your disk has enough room to hold your work and by frequently saving your work.