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diff --git a/share/doc/usd/11.vitut/edittut.ms b/share/doc/usd/11.vitut/edittut.ms new file mode 100644 index 000000000000..8a9d66ede2e6 --- /dev/null +++ b/share/doc/usd/11.vitut/edittut.ms @@ -0,0 +1,2280 @@ +.\" Copyright (c) 1980, 1993 +.\" The Regents of the University of California. All rights reserved. +.\" +.\" Redistribution and use in source and binary forms, with or without +.\" modification, are permitted provided that the following conditions +.\" are met: +.\" 1. Redistributions of source code must retain the above copyright +.\" notice, this list of conditions and the following disclaimer. +.\" 2. Redistributions in binary form must reproduce the above copyright +.\" notice, this list of conditions and the following disclaimer in the +.\" documentation and/or other materials provided with the distribution. +.\" 3. All advertising materials mentioning features or use of this software +.\" must display the following acknowledgement: +.\" This product includes software developed by the University of +.\" California, Berkeley and its contributors. +.\" 4. Neither the name of the University nor the names of its contributors +.\" may be used to endorse or promote products derived from this software +.\" without specific prior written permission. +.\" +.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND +.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE +.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE +.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE +.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL +.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS +.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) +.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT +.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY +.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF +.\" SUCH DAMAGE. +.\" +.\" @(#)edittut.ms 8.3 (Berkeley) 8/18/96 +.\" +.ll 6.5i +.nr LL 6.5i +.EH 'USD:11-%''Edit: A Tutorial' +.OH 'Edit: A Tutorial''USD:11-%' +.LP +.ds u \s-2UNIX\s0 +.ND +.sp 4 +.ce +\f3\s+2Edit: A Tutorial\s0\f1 +.sp +.ce 3 +.I +Ricki Blau +.sp +James Joyce +.R +.sp +.ce 3 +Computing Services +University of California +Berkeley, California 94720 +.sp 3 +.ce +.I +ABSTRACT +.R +.sp +.LP +This narrative introduction to the use of the text editor +.I edit +assumes no prior familiarity with computers or with text editing. +Its aim is to lead the beginning \s-2UNIX\(dg\s+2 user through the +.FS +\(dgUNIX is a trademark of Bell Laboratories. +.FE +fundamental steps of writing and revising a file of text. +Edit, +a version of the text editor +.I ex, +was designed to provide an informative environment +for new and casual users. +.PP +We welcome comments and suggestions about this tutorial +and the \s-2UNIX\s+2 documentation in general. +.sp .5v +September 1981 +.bp +.ll 6.5i +.nr LL 6.5i +.nr LT 6.5i +.ds u \s-2UNIX\s0 +.ce +\s+2\f3Contents\f1\s0 +.LP +.nf +Introduction\ \ \ 3 +.sp +Session 1\ \ 4 +.in +.5i +Making contact with \s-2UNIX\s+2\ \ \ 4 +Logging in\ \ 4 +Asking for \fIedit\fR\ \ \ 4 +The ``Command not found'' message\ \ \ 5 +A summary\ \ 5 +Entering text\ \ \ 5 +Messages from \fIedit\fR\ \ \ 5 +Text input mode\ \ \ 6 +Making corrections\ \ \ 6 +Writing text to disk\ \ \ 7 +Signing off\ \ 7 +.in -.5i +.sp +Session 2\ \ \ 8 +.in +.5i +Adding more text to the file\ \ \ 8 +Interrupt\ \ \ 8 +Making corrections\ \ \ 8 +Listing what's in the buffer (p)\ \ \ 9 +Finding things in the buffer\ \ \ 9 +The current line\ \ \ 10 +Numbering lines (nu)\ \ \ 10 +Substitute command (s)\ \ \ 10 +Another way to list what's in the buffer (z)\ \ \ 11 +Saving the modified text\ \ \ 12 +.in -.5i +.sp +Session 3\ \ \ 13 +.in +.5i +Bringing text into the buffer (e)\ \ \ 13 +Moving text in the buffer (m)\ \ \ 13 +Copying lines (copy)\ \ \ 14 +Deleting lines (d)\ \ \ 14 +A word or two of caution\ \ \ 15 +Undo (u) to the rescue\ \ \ 15 +More about the dot (.) and buffer end ($)\ \ \ 16 +Moving around in the buffer (+ and \-)\ \ \ 16 +Changing lines (c)\ \ \ 17 +.in -.5i +.sp +Session 4\ \ \ 18 +.in +.5i +Making commands global (g)\ \ \ 18 +More about searching and substituting\ \ \ 19 +Special characters\ \ \ 19 +Issuing \s-2UNIX\s+2 commands from the editor\ \ \ 20 +Filenames and file manipulation\ \ \ 20 +The file (f) command\ \ \ 20 +Reading additional files (r)\ \ \ 21 +Writing parts of the buffer\ \ \ 21 +Recovering files\ \ \ 21 +Other recovery techniques\ \ \ 21 +Further reading and other information\ \ \ 22 +Using \fIex\fR\ \ \ 22 +.in -.5i +.sp +Index\ \ \ 23 +.bp +.SH +.ce +\s+2Introduction\s0 +.PP +Text editing using a terminal connected to a computer +allows you to create, modify, and print text +easily. +A +.I +text editor +.R +is a program +that assists you +as you create and modify text. +The text editor you will learn here is named +.I edit. +Creating text using edit is as easy as typing it +on an electric typewriter. +Modifying text involves telling the text editor +what you want to add, change, or delete. +You can review your text +by typing a command +to print the file contents +as they are currently. +Another program (which we do not discuss in this +document), a text formatter, +rearranges your text +for you into ``finished form.'' +.PP +These lessons assume no prior familiarity with computers +or with text editing. +They consist of a series of text editing sessions +which lead you through the fundamental steps +of creating and revising text. +After scanning each lesson and before beginning the next, +you should try the examples at a terminal to get a feeling +for the actual process of text editing. +If you set aside some time for experimentation, +you will soon become familiar with using the +computer to write and modify text. +In addition to the actual use of the text editor, +other features of \s-2UNIX\s0 will be very important to your work. +You can begin to +learn about these other features by +reading one of the other tutorials +that provide a general introduction to the system. +You will be ready to proceed with this lesson as soon as +you are familiar with (1) your terminal and its special keys, +(2) how to login, +(3) and the ways of correcting typing errors. +Let's first define some terms: +.sp .5 +.IP program 12 +A set of instructions, given to the computer, +describing the sequence of steps the computer performs +in order to accomplish a specific task. +The task must be specific, +such as balancing your checkbook +or editing your text. +A general task, +such as working for world peace, +is something we can all do, +but not something we can currently write programs to do. +.IP UNIX +\s-2UNIX\s0 is a special type of program, +called an operating system, that supervises the machinery +and all other programs comprising the total +computer system. +.IP edit +.I edit +is the name of the \s-2UNIX\s0 text editor you will be learning to use, +and is a program that aids you in writing or revising text. +Edit was designed for beginning users, +and is a simplified version of an editor named +.I ex. +.IP file +Each \s-2UNIX\s0 account is allotted +space for the permanent storage of information, +such as programs, data or text. +A file is a logical unit of data, +for example, an essay, a program, +or a chapter from a book, +which is stored on a computer system. +Once you create a file, +it is kept until you instruct the system to remove it. +You may create a file during one \s-2UNIX\s0 session, +end the session, +and return to use it at a later time. +Files contain anything you choose to write and store in them. +The sizes of files vary to suit your needs; +one file might hold only a single number, +yet another might contain +a very long document or program. +The only way to save +information from one session to the next is to store it in a file, +which you will learn in Session 1. +.IP filename +Filenames are used to distinguish one file from another, +serving the same purpose as the labels of manila +folders in a file cabinet. +In order to write or access information in a file, +you use the name of that file in a \s-2UNIX\s0 command, +and the system will automatically locate the file. +.IP disk +Files are stored on an input/output device called a disk, +which looks something like a stack of phonograph records. +Each surface is coated with a material similar to that +on magnetic recording tape, +and information is recorded on it. +.IP buffer +A temporary work space, made available to the user +for the duration of a session of text editing +and used for creating and modifying +the text file. +We can think of the buffer as a blackboard that is +erased after each class, where each session with the editor +is a class. +.bp +.SH +.ce 1 +\s+2Session 1\s0 +.sp 1 +.SH +Making contact with \s-1UNIX\s0 +.PP +To use the editor you must first make contact with the computer +by logging in to \s-2UNIX\s0. +We'll quickly review the standard \s-2UNIX\s0 login procedure +for the two ways you can make contact: +on a terminal that is directly linked to the computer, +or over a telephone line where the computer answers your call. +.SH +Directly-linked terminals +.PP +Turn on your terminal and press the \s-1RETURN\s0 key. +You are now ready to login. +.SH +Dial-up terminals +.PP +If your terminal connects with the computer over a telephone line, +turn on the terminal, dial the system access number, +and, when you hear a high-pitched tone, place the +telephone handset in the acoustic coupler, if you are using one. +You are now ready to login. +.SH +Logging in +.PP +The message inviting you to login is: +.DS I 1i +login: +.DE +.LP +Type your login name, which identifies you to \s-2UNIX\s0, +on the same line as the login message, +and press \s-2RETURN\s+2. +If the terminal you are using +has both upper and lower case, +.B +be sure you enter your login name in lower case; +.R +otherwise \s-2UNIX\s0 assumes your terminal +has only upper case and will not recognize lower case +letters you may type. +\s-2UNIX\s0 types ``login:'' and you reply +with your login name, for example ``susan'': +.DS I 1i +login: \fBsusan\fR \fI(and press the \s-2RETURN\s0 key)\fR +.DE +(In the examples, input you would type appears in +.B "bold face" +to distinguish it from the responses from \s-2UNIX\s0.) +.PP +\s-2UNIX\s0 will next respond with a request for a password +as an additional precaution to prevent +unauthorized people from using your account. +The password will not appear when you type it, +to prevent others from seeing it. +The message is: +.DS I 1i +Password: \fI(type your password and press \s-2RETURN\s+2)\fR +.DE +If any of the information you gave during the login +sequence was mistyped or incorrect, +\s-2UNIX\s0 will respond with +.DS I 1i +Login incorrect. +.if t .sp .2v +.if n .sp 1 +login: +.DE +in which case you should start the login process anew. +Assuming that you have successfully +logged in, \s-2UNIX\s0 +will print the message of the day and eventually will present +you with a % at the beginning of a fresh line. +The % is the \s-2UNIX\s0 prompt symbol +which tells you that \s-2UNIX\s0 is ready to accept a command. +.bd I 3 +.SH +Asking for \fIedit\fP +.fl +.bd I +.PP +You are ready to tell \s-2UNIX\s0 that you +want to work with edit, the text editor. +Now is a convenient time to choose +a name for the file of text you are about to create. +To begin your editing session, +type +.B edit +followed by a space and then the filename +you have selected; for example, ``text''. +After that, +press the \s-2RETURN\s0 key and wait for edit's response: +.DS I 1i +% \fBedit text\fP \fI(followed by a \s-2RETURN\s+2)\fR +"text" No such file or directory +: +.DE +If you typed the command correctly, +you will now be in communication with edit. +Edit has set aside a buffer for use as +a temporary working space during your current editing session. +Since ``text'' is a new file we are about to create +the editor was unable to find that file, which it +confirms by saying: +.DS I 1i +"text" No such file or directory +.DE +On the next line appears edit's prompt ``:'', +announcing that you are in \f2command mode\f1 and +edit expects a command from you. +You may now begin to create the new file. +.SH +The ``Command not found'' message +.PP +If you misspelled edit by typing, say, ``editor'', +this might appear: +.DS I 1i +% \fBeditor\fP +editor: Command not found +% +.DE +Your mistake in calling edit ``editor'' was +treated by \s-2UNIX\s0 as a request +for a program named ``editor''. +Since there is no program +named ``editor'', +\s-2UNIX\s0 reported that the program was ``not found''. +A new % indicates that \s-2UNIX\s0 is ready for another command, +and you may then enter the correct command. +.SH +A summary +.PP +Your exchange with \s-2UNIX\s0 as you logged in and made contact with edit +should look something like this: +.DS I 1i +login: \fBsusan\fP +Password: +\&... A Message of General Interest ... +% \fBedit text\fP +"text" No such file or directory +: +.DE +.SH +Entering text +.PP +You may now begin entering text into the buffer. +This is done by \fIappending\fP (or adding) text to whatever +is currently in the buffer. +Since there is nothing in the buffer at the moment, +you are appending text to nothing; +in effect, +since you are adding text to nothing +you are creating text. +Most edit commands have two equivalent forms: +a word that suggests what the command does, +and a shorter abbreviation of that word. +Many beginners find the full command names +easier to remember at first, +but once you are familiar with editing you may +prefer to type the shorter abbreviations. +The command to input text is ``append''. +(It may be abbreviated ``a''.) +Type +.B append +and press the \s-2RETURN\s0 key. +.DS I 1i +% \fBedit text +\fR:\|\fBappend +.R +.DE +.SH +.bd I 3 +Messages from +.I edit +.fl +.bd I +.PP +If you make a mistake in entering a command and +type something that edit does not recognize, +edit will respond with a message +intended to help you diagnose your error. +For example, if you misspell the command to input text by typing, +perhaps, ``add'' instead of ``append'' or ``a'', +you will receive this message: +.DS I 1i +:\|\fBadd\fR +add: Not an editor command +: +.DE +When you receive a diagnostic message, +check what you typed in order to determine what +part of your command confused edit. +The message above means that edit +was unable to recognize your mistyped command +and, therefore, did not execute it. +Instead, a new ``:'' +appeared to let you know that +edit is again ready to execute a command. +.SH +Text input mode +.PP +By giving the command ``append'' (or using the abbreviation ``a''), +you entered +.I +text input mode, +.R +also known as +.I +append mode. +.R +When you enter text input mode, +edit stops sending you a prompt. +You will not receive any prompts +or error messages +while in text input mode. +You can enter +pretty much anything you want on the lines. +The lines are transmitted one by one to the buffer +and held there during the editing session. +You may append as much text as you want, and +.I +when you wish to stop entering text lines you should +type a period as the only character on the line +and press the \s-2RETURN\s0 key. +.R +When you type the period and press \s-2RETURN\s0, +you signal that you want to stop appending text, +and edit responds by allowing +you to exit text input mode and reenter command mode. +Edit will again +prompt you for a command by printing ``:''. +.PP +Leaving append mode does not destroy the text in +the buffer. +You have to leave append +mode to do any of the other kinds of editing, +such as changing, adding, or printing text. +If you type a period as the first character and +type any other character on the same line, +edit will believe you want to remain in append mode +and will not let you out. +As this can be very frustrating, +be sure to type +.B only +the period and the \s-2RETURN\s0 key. +.PP +This is a good place to learn an important +lesson about computers and text: a blank space is +a character as far as a computer is concerned. +If you so much as type a period followed by a blank +(that is, type a period and then the space bar on the keyboard), +you will remain in append mode with the last line of text +being: +.DS I 1i +.B +.ps +2 +\&. +.ps -2 +.R +.DE +Let's say that you enter the lines +(try to type +.B exactly +what you see, including ``thiss''): +.DS I 1i +.B +This is some sample text. +And thiss is some more text. +Text editing is strange, but nice. +\&. +.R +.DE +The last line is the period followed by a \s-2RETURN\s0 +that gets you out of append mode. +.SH +Making corrections +.PP +If you have read a general introduction to \s-2UNIX\s0, +you will recall that it is possible to erase individual +letters that you have typed. +This is done by typing the designated erase character +as many times as there are characters +you want to erase. +.PP +The usual erase character varies from place to place and +user to user. Often it +is the backspace (control-H), +so you can correct typing errors +in the line you are typing +by holding down the \s-1CTRL\s+1 key +and typing the ``H'' key. (Sometimes it is the DEL key.) +If you type the erase character +you will notice +that the terminal backspaces in the line you are on. +You can backspace over your error, +and then type what you want to be the rest of the line. +.PP +If you make a bad start +in a line +and would like to begin again, +you can either backspace to the beginning of the line +or you can use the at-sign ``@'' to erase everything on the line: +.DS I 1i +.B +Text edtiing is strange, but@ +Text editing is strange, but nice. +.R +.fl +.bd S +.DE +When you type the at-sign (@), you erase +the entire line typed so far +and are given a fresh line to type on. +You may immediately begin to retype the line. +This, unfortunately, does not work after you type the +line and press \s-2RETURN\s+2. +To make corrections in lines that have been completed, +it is necessary to use the editing commands +covered in the next sessions. +.SH +Writing text to disk +.PP +You are now ready to edit the text. One common operation +is to write the text to disk as a file for safekeeping +after the session is over. +This is the only way to save information from one session to the next, +since the editor's buffer is temporary and will last only until the +end of the editing session. +Learning how to write a file to disk is second in +importance only to entering the text. +To write the contents of the buffer to a disk +file, use the command ``write'' +(or its abbreviation ``w''): +.DS I 1i +:\|\fBwrite +.R +.DE +Edit will copy the contents of the buffer to a disk file. +If the file does not yet exist, +a new file will be created automatically +and the presence of a ``[New file]'' will be noted. +The newly-created file will be given the name specified when +you entered the editor, in this case ``text''. +To confirm that the disk file has been successfully written, +edit will repeat the filename and give +the number of lines and the total +number of characters in the file. +The buffer remains unchanged by the ``write'' command. +All of the lines that were written to disk will still be +in the buffer, +should you want to modify or add to them. +.PP +Edit must have a name for the file to be written. +If you forgot to indicate the name of the file +when you began to edit, +edit will print in response to your write command: +.DS I 1i +No current filename +.DE +If this happens, you can specify the filename in a new write command: +.DS I 1i +:\|\fBwrite text +.R +.DE +After the ``write'' (or ``w''), type a space and then the name of the file. +.SH +Signing off +.PP +We have done enough for this first lesson on using the +\s-2UNIX\s0 text editor, and are ready to quit the session with edit. +To do this we type ``quit'' (or ``q'') and press \s-2RETURN\s+2: +.DS I 1i +:\|\fBwrite +.R +"text" [New file] 3 lines, 90 characters +:\|\fBquit\fR +% +.DE +The % is from \s-2UNIX\s0 to tell you that your session with edit is +over and you may command \s-2UNIX\s0 further. +Since we want +to end the entire session at the terminal, we also need to +exit from \s-2UNIX\s0. +In response to the \s-2UNIX\s0 prompt of ``\|%\|'' +type the command +.DS I 1i +%\|\fBlogout\fR +.DE +This will end your session with \s-2UNIX\s0, and will ready the +terminal for the next user. +It is always important to type \fBlogout\fR at the end of a session +to make absolutely sure no one +could accidentally stumble into your abandoned +session and thus gain access to your files, +tempting even the most honest of souls. +.sp 1 +.PP +This is the end of the first session on \s-2UNIX\s0 text editing. +.bp +.TL +Session 2 +.sp +.PP +Login with \s-2UNIX\s0 as in the first session: +.DS I 1i +login: \fBsusan\fP \fI(carriage return)\fR +Password: \fI(give password and carriage return)\fR +.if t .sp .2v +.if n .sp 1 +\&... A Message of General Interest ... +% +.DE +When you indicate you want to edit, +you can specify the name of the file you worked on last time. +This will +start edit working, and it will fetch the contents of the +file into the buffer, so that you can resume editing the same file. +When edit has copied the file into the buffer, it +will repeat its name and tell +you the number of lines and characters it contains. +Thus, +.DS I 1i +.B +% edit text +.R +"text" 3 lines, 90 characters +: +.DE +means you asked edit to fetch +the file named ``text'' for editing, +causing it to copy the +90 characters of text into the buffer. +Edit awaits +your further instructions, +and indicates this by its prompt character, the colon (:). +In this session, we will append more text to our file, +print the contents of the buffer, and learn to change the text of a line. +.SH +Adding more text to the file +.PP +If you want to add more to the end of your +text you may do so by using the append command to enter text input mode. +When ``append'' is the first command +of your editing session, +the lines you enter +are placed at the end of the buffer. +Here we'll use the abbreviation for the append command, ``a'': +.DS I 1i +:\|\fBa +This is text added in Session 2. +It doesn't mean much here, but +it does illustrate the editor. +\|\fB\s+2\&.\s-2 +.R +.DE +You may recall that once you enter append mode +using the ``a'' (or ``append'') command, +you need to type a line containing only a period (.) +to exit append mode. +.SH +Interrupt +.PP +Should you press the \s-2RUB\s+2 key (sometimes labelled \s-2DELETE\s+2) +while working with edit, +it will send this message to you: +.DS I 1i +Interrupt +: +.DE +Any command that edit might be executing +is terminated by rub or delete, +causing edit to prompt you for a new command. +If you are appending text at the time, +you will exit from append mode +and be expected to give another command. +The line of text you were typing +when the append command was interrupted +will not be entered into the buffer. +.SH +Making corrections +.PP +If while typing the line you hit an incorrect key, +recall that +you may delete the incorrect character +or cancel the entire line of input by erasing in the usual way. +Refer either +to the last few pages of Session 1 +if you need to review +the procedures for making a correction. +The most important idea to remember is that +erasing a character or cancelling a line must be done +before you press the \s-2RETURN\s+2 key. +.SH +Listing what's in the buffer (p) +.PP +Having appended text to what you wrote in Session 1, +you might want to see all the lines in the buffer. +To print the contents of the buffer, type the command: +.DS I 1i +:\|\fB1,$p +.R +.DE +The ``1''\(dg +.FS +\(dgThe numeral ``one'' is the top left-most key, +and should not be confused with the letter ``el''. +.FE +stands for line 1 of the buffer, +the ``$'' is a special symbol designating the last line +of the buffer, +and ``p'' (or \fBprint\fR) is the command to print from line 1 +to the end of the buffer. +The command ``1,$p'' gives you: +.DS I 1i +This is some sample text. +And thiss is some more text. +Text editing is strange, but nice. +This is text added in Session 2. +It doesn't mean much here, but +it does illustrate the editor. +.DE +Occasionally, you may accidentally +type a character that can't be printed, +which can be done by striking a key +while the \s-2CTRL\s0 key is pressed. +In printing lines, edit uses a special notation to +show the existence of non-printing characters. +Suppose you had introduced the non-printing character ``control-A'' +into the word ``illustrate'' +by accidently pressing the \s-2CTRL\s0 key while +typing ``a''. +This can happen on many terminals +because the \s-2CTRL\s+2 key and the ``A'' key +are beside each other. +If your finger presses between the two keys, +control-A results. +When asked to print the contents of the buffer, +edit would display +.DS I 1i +it does illustr^Ate the editor. +.DE +To represent the control-A, edit shows ``^A''. +The sequence ``^'' followed by a capital +letter stands for the one character +entered by holding down the \s-2CTRL\s0 key and typing the letter +which appears after the ``^''. +We'll soon discuss the commands that can be used +to correct this typing error. +.PP +In looking over the text we see that +``this'' is typed as ``thiss'' in the second line, +a deliberate error so we can learn to make corrections. +Let's correct the spelling. +.SH +Finding things in the buffer +.PP +In order to change something in the buffer we first need to +find it. +We can find ``thiss'' in the text we have +entered by looking at a listing +of the lines. +Physically speaking, we search the lines +of text looking for ``thiss'' and stop searching when +we have found it. +The way to tell edit to search for something +is to type it inside slash marks: +.DS I 1i +:\|\fB/thiss/ +.R +.DE +By typing +.B /thiss/ +and pressing \s-1RETURN\s0, +you instruct edit to search for ``thiss''. +If you ask edit to look for a pattern of characters +which it cannot find in the buffer, +it will respond ``Pattern not found''. +When edit finds +the characters ``thiss'', it will print the line of text +for your inspection: +.DS I 1i +And thiss is some more text. +.DE +Edit is now positioned in the buffer at the +line it just printed, +ready to make a change in the line. +.bp +.SH +The current line +.PP +Edit keeps track of the line in the buffer where it is located +at all times during an editing session. +In general, the line that has been most recently +printed, entered, or changed +is the current location in the buffer. +The editor is prepared to make changes +at the current location in the buffer, +unless you direct it to another location. +.PP +In particular, +when you bring a file into the buffer, +you will be located at the last line in the file, +where the editor left off copying the lines +from the file to the buffer. +If your first editing command is ``append'', +the lines you enter are added +to the end of the file, +after the current line \(em +the last line in the file. +.PP +You can refer to your current location in the buffer by the +symbol +period (.) usually known by the name ``dot''. +If you type ``.'' and carriage +return you will be instructing edit to print the current line: +.DS I 1i +:\|\fB\s+2\&.\s-2 +.R +And thiss is some more text. +.DE +.PP +If you want to know the number of the current line, +you can type +.B \&.= +and press \s-2RETURN\s+2, +and edit will respond with the line number: +.DS I 1i +:\|\fB\s+2.\s-2= +.R +2 +.DE +If you type the number of any line and press \s-2RETURN\s+2, +edit will position you at that line and +print its contents: +.DS I 1i +:\|\fB2 +.R +And thiss is some more text. +.DE +You should experiment with these commands +to gain experience in using them to make changes. +.SH +Numbering lines (nu) +.PP +The +.B +number (nu) +.R +command is similar to print, +giving both the number and the text of each printed line. +To see the number and the text of the current line type +.DS I 1i +:\|\fBnu +.R +\0\0\0\0\02\0\0And thiss is some more text. +.DE +Note that the shortest abbreviation for the number command is +``nu'' (and not ``n'', which is used for a different command). +You may specify a range of lines +to be listed by the number command in the same way that lines +are specified for print. +For example, \f31,$nu\f1 lists all lines in the buffer with their +corresponding line numbers. +.SH +Substitute command (s) +.PP +Now that you have found the misspelled word, +you can change it from ``thiss'' to ``this''. +As far as edit is concerned, +changing things is a matter of +substituting one thing for another. +As +.I a +stood for +.I append, +so +.I s +stands for +.I substitute. +We will use the abbreviation ``s'' to reduce the chance +of mistyping the substitute command. +This command will instruct edit to make the change: +.DS I 1i +\f32s/thiss/this/\f1 +.DE +We first indicate the line to be changed, line 2, +and then +type an ``s'' to indicate we want +edit to make a substitution. +Inside the first set of slashes +are the characters that we want to change, +followed by the characters to replace them, +and then a closing slash mark. +To summarize: +.DS I 1i +2s/ \fIwhat is to be changed\fR / \fIwhat to change it to \fR/ +.DE +If edit finds an exact match of the characters to be +changed it will make the change +.B only +in the first occurrence of the characters. +If it does not find the characters +to be changed, it will respond: +.DS I 1i +Substitute pattern match failed +.DE +indicating that your instructions could not be carried out. +When edit does find the characters that you want to change, +it will make the substitution and automatically print +the changed line, so that you can check that the correct substitution +was made. +In the example, +.DS I 1i +:\|\fB2s/thiss/this/ +.R +And this is some more text. +.DE +line 2 (and line 2 only) will be searched for the characters +``thiss'', and when the first exact match is found, ``thiss'' +will be changed to ``this''. +Strictly speaking, it was not necessary above to +specify the number of the line to be changed. +In +.DS I 1i +:\|\fBs/thiss/this/ +.R +.DE +edit will assume that we mean to change +the line where we are currently located (``.''). +In this case, +the command without a line number would have produced the same result +because we were already located +at the line we wished to change. +.PP +For another illustration of the substitute command, +let us choose the line: +.DS I 1i +Text editing is strange, but nice. +.DE +You can make this line a bit more positive +by taking out the characters ``strange, but\ '' so the line +reads: +.DS I 1i +Text editing is nice. +.DE +A command that will first position edit at the desired line +and then make the substitution is: +.DS I 1i +:\|\fB/strange/s/strange, but // +.R +.DE +.LP +What we have done here is combine our search with +our substitution. +Such combinations are perfectly legal, +and speed up editing quite a bit +once you get used to them. +That is, you do not necessarily have to use +line numbers to identify a line to edit. +Instead, you may identify the line you want to change +by asking edit to search for a specified pattern of letters +that occurs in that line. +The parts of the above command are: +.in +1i +.TS +l l. +\fB/strange/\fP tells edit to find the characters ``strange'' in the text +\fBs\fP tells edit to make a substitution +\fB/strange, but //\fP substitutes nothing at all for the characters ``strange, but '' +.TE +.in -1i +.PP +You should note the space after ``but'' in ``/strange, but /''. +If you do not indicate that the space is to be taken out, +your line will read: +.DS I 1i +.if t Text editing is nice. +.if n Text editing is nice. +.DE +which looks a little funny +because of the extra space between ``is'' and ``nice''. +Again, we realize from this that a blank space +is a real character to a computer, and in editing text +we need to be aware of spaces +within a line just as we would be aware of an ``a'' or +a ``4''. +.SH +Another way to list what's in the buffer (z) +.PP +Although the print command is useful for looking at specific lines +in the buffer, +other commands may be more convenient for +viewing large sections of text. +You can ask to see a screen full of text at a time +by using the command +.B z. +If you type +.DS I 1i +:\|\fB1z +.R +.DE +edit will start with line 1 and continue printing lines, +stopping either when the screen of +your terminal is full +or when the last line in the buffer has been printed. +If you want to read the next segment of text, type the command +.DS I 1i +:\|\fBz +.DE +If no starting line number is given for the z command, +printing will start at the ``current'' line, in this case the +last line printed. +Viewing lines in the buffer one screen full at a time +is known as \fIpaging\fR. +Paging can also be used to print +a section of text on a hard-copy terminal. +.SH +Saving the modified text +.PP +This seems to be a good place to pause in our work, +and so we should end the second session. +If you (in haste) type ``q'' to quit the session +your dialogue with edit will be: +.DS I 1i +:\|\fBq +.R +No write since last change (:quit! overrides) +: +.DE +This is edit's warning that you have not written +the modified contents of the buffer to disk. +You run the risk of losing the work you did +during the editing session since you typed the latest write +command. +Because in this lesson we have not written +to disk at all, everything we have done +would have been lost +if edit had obeyed the \fBq\fR command. +If you did not want to save the work done during +this editing session, you would have to type ``q!'' +or (``quit!'') +to confirm that you indeed wanted to end the session +immediately, +leaving the file as it was +after the most recent ``write'' command. +However, +since you want to save what +you have edited, you need to type: +.DS I 1i +:\|\fBw +.R +"text" 6 lines, 171 characters +.DE +and then follow with the commands to quit and logout: +.DS I 1i +:\|\fBq +% \fBlogout\fR +.DE +and hang up the phone or turn off the terminal when +\s-2UNIX\s0 asks for a name. +Terminals connected to the port selector +will stop after the logout command, +and pressing keys on the keyboard will do nothing. +.sp 1 +.PP +This is the end of the second session on \s-2UNIX\s0 text editing. +.bp +.TL +Session 3 +.SH +Bringing text into the buffer (e) +.PP +Login to \s-2UNIX\s0 and make contact with edit. +You should try to login without +looking at the notes, but if you must +then by all means do. +.PP +Did you remember to give the name of the file +you wanted to edit? +That is, did you type +.DS I 1i +% \fBedit text\fR +.DE +or simply +.DS I 1i +% \fBedit\fR +.DE +Both ways get you in contact with edit, but the first way +will bring a copy of the file named ``text'' into +the buffer. +If you did forget to tell edit the name of your file, +you can get it into the buffer by +typing: +.DS I 1i +:\|\fBe text +.R +"text" 6 lines, 171 characters +.DE +The command +.B edit, +which may be abbreviated \fBe\fR, +tells edit that you want +to erase anything that might already be in +the buffer and bring a copy of the file ``text'' into the buffer +for editing. +You may also use the edit (e) command to change files in +the middle of an editing session, +or to give edit the name of a new file that you want to create. +Because the edit command clears the buffer, +you will receive a warning if you try to edit a new file without +having saved a copy of the old file. +This gives you a chance to write the contents of the buffer to disk +before editing the next file. +.SH +Moving text in the buffer (m) +.PP +Edit allows you to move lines of text +from one location in the buffer to another +by means of the +.B move +(\fBm\fR) command. +The first two examples are for illustration only, +though after you have read this Session +you are welcome to return to them for practice. +The command +.DS I 1i +:\|\fB2,4m$ +.R +.DE +directs edit to move lines 2, 3, and 4 +to the end of the buffer ($). +The format for the move command is that you specify +the first line to be moved, the last line to be moved, +the move command ``m'', and the line after which +the moved text is to be placed. +So, +.DS I 1i +:\|\fB1,3m6 +.R +.DE +would instruct edit to move lines 1 through 3 (inclusive) +to a location after line 6 in the buffer. +To move only one line, say, line 4, +to a location in the buffer after line 5, +the command would be ``4m5''. +.PP +Let's move some text using the command: +.DS I 1i +:\|\fB5,$m1 +.R +2 lines moved +it does illustrate the editor. +.DE +After executing a command that moves more than one line of the buffer, +edit tells how many lines were affected by the move +and prints the last moved line for your inspection. +If you want to see more than just the last line, +you can then +use the print (p), z, or number (nu) command to view more text. +The buffer should now contain: +.DS I 1i +This is some sample text. +It doesn't mean much here, but +it does illustrate the editor. +And this is some more text. +Text editing is nice. +This is text added in Session 2. +.DE +You can restore the original order by typing: +.DS I 1i +:\|\fB4,$m1 +.R +.DE +or, combining context searching and the move command: +.DS I 1i +:\|\fB/And this is some/,/This is text/m/This is some sample/ +.R +.DE +(Do not type both examples here!) +The problem with combining context searching +with the move command +is that your chance of making a typing error +in such a long command is greater than +if you type line numbers. +.SH +Copying lines (copy) +.PP +The +.B copy +command +is used to make a second copy of specified lines, +leaving the original lines where they were. +Copy +has the same format as the move command, for example: +.DS I 1i +:\|\fB2,5copy $ +.R +.DE +makes a copy of lines 2 through 5, +placing the added lines after the buffer's end ($). +Experiment with the copy command +so that you can become familiar with how it works. +Note that the shortest abbreviation for copy is +\f3co\f1 (and +not the letter ``c'', which has another meaning). +.SH +Deleting lines (d) +.PP +Suppose you want to delete +the line +.DS I 1i +This is text added in Session 2. +.DE +from the buffer. +If you know the number of the line to be deleted, +you can type +that number followed by +\fBdelete\fR or \fBd\fR. +This example deletes line 4, +which is ``This is text added in Session 2.'' +if you typed the commands +suggested so far. +.DS I 1i +:\|\fB4d +.R +It doesn't mean much here, but +.DE +Here ``4'' is the number of the line to be deleted, +and ``delete'' or ``d'' is the command to delete the line. +After executing the delete command, +edit prints the line that has become the current line (``.''). +.PP +If you do not happen to know the line number +you can search for the line and then delete it using this +sequence of commands: +.DS I 1i +:\|\fB/added in Session 2./ +.R +This is text added in Session 2. +:\|\fBd +.R +It doesn't mean much here, but +.DE +The ``/added in Session 2./'' +asks edit to locate and print +the line containing the indicated text, +starting its search at the current line +and moving line by line +until it finds the text. +Once you are sure that you have correctly specified the line +you want to delete, +you can enter the delete (d) command. +In this case it is not necessary to +specify a line number before the ``d''. +If no line number is given, +edit deletes the current line (``.''), +that is, the line found by our search. +After the deletion, your buffer should contain: +.DS I 1i +This is some sample text. +And this is some more text. +Text editing is nice. +It doesn't mean much here, but +it does illustrate the editor. +And this is some more text. +Text editing is nice. +This is text added in Session 2. +It doesn't mean much here, but +.DE +To delete both lines 2 and 3: +.DS I 1i +And this is some more text. +Text editing is nice. +.DE +you type +.DS I 1i +:\|\f32,3d\f1 +2 lines deleted +.DE +which specifies the range of lines from 2 to 3, +and the operation on those lines \(em ``d'' for delete. +If you delete more than one line +you will receive a message +telling you the number of lines deleted, +as indicated in the example above. +.PP +The previous example assumes that you know the line numbers for +the lines to be deleted. +If you do not you might combine the search command +with the delete command: +.DS I 1i +:\|\fB/And this is some/,/Text editing is nice./d +.R +.DE +.SH +A word or two of caution +.PP +In using the search function to locate lines to +be deleted you should be +.B +absolutely sure +.R +the characters you give as the basis for the search +will take edit to the line you want deleted. +Edit will search for the first +occurrence of the characters starting from where +you last edited \- +that is, from the line you see printed if you type dot (.). +.PP +A search based on too few +characters may result in the wrong lines being deleted, +which edit will do as easily as if you had meant it. +For this reason, it is usually safer +to specify the search and then delete in two separate steps, +at least until you become familiar enough with using the editor +that you understand how best to specify searches. +For a beginner it is not a bad idea to double-check +each command before pressing \s-2RETURN\s+2 to send the command on its way. +.SH +Undo (u) to the rescue +.PP +The +.B +undo (u) +.R +command has the ability to +reverse the effects of the last command that changed the buffer. +To undo the previous command, type +``u'' or ``undo''. +Undo can rescue +the contents of the buffer from many an unfortunate mistake. +However, its powers are not unlimited, +so it is still wise to be reasonably +careful about the commands you give. +.PP +It is possible to undo only commands which +have the power to change the buffer \(em for example, +delete, append, move, copy, substitute, and even undo itself. +The commands write (w) and edit (e), which interact with disk files, +cannot be undone, nor can commands that do not change +the buffer, such as print. +Most importantly, +the +.B only +command that can be reversed by undo +is the +last ``undo-able'' command you typed. +You can use control-H and @ to change +commands while you are typing them, +and undo to reverse the effect of the commands +after you have typed them and pressed \s-2RETURN\s+2. +.PP +To illustrate, +let's issue an undo command. +Recall that the last buffer-changing command we gave deleted +the lines formerly numbered 2 and 3. +Typing undo at this moment will reverse the effects +of the deletion, causing those two lines to be +replaced in the buffer. +.DS I 1i +:\|\fBu +.R +2 more lines in file after undo +And this is some more text. +.DE +Here again, edit informs you if the command affects more +than one line, +and prints +the text of the line which is now ``dot'' (the current line). +.SH +More about the dot (.) and buffer end ($) +.PP +The function assumed by the symbol dot depends on its context. +It can be used: +.IP +1. to exit from append mode; we type dot (and only a dot) on +a line and press \s-2RETURN\s+2; +.IP +2. to refer to the line we are at in the buffer. +.LP +Dot can also be combined with the equal sign to get +the number of the line currently being edited: +.DS I 1i +:\|\fB\&.= +.R +.DE +If we type ``\fB.\fR='' we are asking for the number of the line, +and if we type ``\fB.\fR'' we are asking for the text of the line. +.PP +In this editing session and the last, we used the dollar +sign to indicate the end of the buffer +in commands such as print, copy, and move. +The dollar sign as a command asks edit to print the last +line in the buffer. +If the dollar sign is combined with the equal sign (\f3$=\f1) +edit will print the line number corresponding to the +last line in the buffer. +.PP +``\fB.\fR'' and ``$'', then, represent line numbers. +Whenever appropriate, these symbols can be used in +place of line numbers in commands. +For example +.DS I 1i +:\|\fB\s+2.\s-2,$d +.R +.DE +instructs edit to delete all lines from the current line (\fB.\fR) +to the end of the buffer. +.SH +Moving around in the buffer (+ and \-) +.PP +When you are editing +you often want +to go back and re-read a previous line. +You could specify a context search for a line you want to +read if you remember some of its text, +but if you simply want to see what was written a few, say 3, lines +ago, you can type +.DS I 1i +\-3p +.DE +This tells edit to move back to a position 3 lines +before the current line (.) +and print that line. +You can move forward in the buffer similarly: +.DS I 1i ++2p +.DE +instructs edit to print the line that is 2 +ahead of your current position. +.PP +You may use ``+'' and ``\-'' in any command where edit +accepts line numbers. +Line numbers specified with ``+'' or ``\-'' +can be combined to print a range of lines. +The command +.DS I 1i +:\|\fB\-1,+2copy$ +.R +.DE +makes a copy of 4 lines: the current line, the line before it, +and the two after it. +The copied lines will be placed after the last line +in the buffer ($), +and the original lines referred to by ``\-1'' and ``+2'' +remain where they are. +.PP +Try typing only ``\-''; you will move back one line just as +if you had typed ``\-1p''. +Typing the command ``+'' works similarly. +You might also try typing a few plus or minus signs in a row +(such as ``+++'') to see edit's response. +Typing \s-2RETURN\s+2 alone on a line is the equivalent +of typing ``+1p''; it will move you one line ahead in the buffer +and print that line. +.PP +If you are at the last line of the buffer and try +to move further ahead, perhaps by typing a ``+'' or +a carriage return alone on the line, +edit will remind you that you are at the end of the buffer: +.sp +.nf +.ti 1i +At end-of-file +.br +or +.ti 1i +Not that many lines in buffer +.fi +.LP +Similarly, if you try to move to a position before the first line, +edit will print one of these messages: +.sp +.nf +.ti 1i +Nonzero address required on this command +.br +or +.ti 1i +Negative address \- first buffer line is 1 +.fi +.LP +The number associated with a buffer line is the line's ``address'', +in that it can be used to locate the line. +.SH +Changing lines (c) +.PP +You can also delete certain lines and +insert new text in their place. +This can be accomplished easily with the +.B "change (c)" +command. +The change command instructs edit to delete specified lines +and then switch to text input mode to +accept the text that will replace them. +Let's say you want to change the first two lines in the buffer: +.DS I 1i +This is some sample text. +And this is some more text. +.DE +to read +.DS I 1i +This text was created with the \s-2UNIX\s0 text editor. +.DE +To do so, you type: +.DS I 1i +:\|\fB1,2c +.R +2 lines changed +.B +This text was created with the \s-2UNIX\s0 text editor. +\s+2\&.\s-2 +.R +: +.DE +In the command +.B 1,2c +we specify that we want to change +the range of lines beginning with 1 and ending with 2 +by giving line numbers as with the print command. +These lines will be deleted. +After you type \s-2RETURN\s+2 to end the change command, +edit notifies you if more than one line will be changed +and places you in text input mode. +Any text typed on the following lines will be inserted into +the position where lines were deleted by the change command. +.B +You will remain in text input mode until you exit in the usual way, +by typing a period alone on a line. +.R +Note that the number of lines added to the buffer need not be +the same as the number of lines deleted. +.sp 1 +.PP +This is the end of the third session on text editing with \s-2UNIX\s0. +.bp +.SH +.ce 1 +\s+2Session 4\s0 +.sp +.PP +This lesson covers several topics, starting with +commands that apply throughout the buffer, +characters with special meanings, +and how to issue \s-2UNIX\s0 commands while in the editor. +The next topics deal with files: +more on reading and writing, +and methods of recovering files lost in a crash. +The final section suggests sources of further information. +.SH +Making commands global (g) +.PP +One disadvantage to the commands we have used for +searching or substituting is that if you +have a number of instances of a word to change +it appears that you have to type the command +repeatedly, once for +each time the change needs to be made. +Edit, however, provides a way to make commands +apply to the entire contents of the buffer \- +the +.B +global (g) +.R +command. +.PP +To print all lines +containing a certain sequence of characters +(say, ``text'') +the command is: +.DS I 1i +:\|\fBg/text/p +.R +.DE +The ``g'' instructs edit to +make a global search for all lines +in the buffer containing the characters ``text''. +The ``p'' prints the lines found. +.PP +To issue a global command, start by typing a ``g'' and then a search +pattern identifying +the lines to be affected. +Then, on the same line, type the command to be +executed for the identified lines. +Global substitutions are frequently useful. +For example, +to change all instances of the word ``text'' to the word ``material'' +the command would be a combination of the global search and the +substitute command: +.DS I 1i +:\|\fBg/text/s/text/material/g +.R +.DE +Note the ``g'' at the end of the global command, +which instructs edit to change +each and every instance of ``text'' to ``material''. +If you do not type the ``g'' at the end of the command +only the +.I first +instance of ``text'' \fIin each line\fR will be changed +(the normal result of the substitute command). +The ``g'' at the end of the command is independent of the ``g'' +at the beginning. +You may give a command such as: +.DS I 1i +:\|\fB5s/text/material/g +.R +.DE +to change every instance of ``text'' in line 5 alone. +Further, neither command will change ``text'' to ``material'' +if ``Text'' begins with a capital rather than a lower-case +.I t. +.PP +Edit does not automatically print the lines modified by a +global command. +If you want the lines to be printed, type a ``p'' +at the end of the global command: +.DS I 1i +:\|\fBg/text/s/text/material/gp +.R +.DE +You should be careful +about using the global command in combination with any other \- +in essence, be sure of what you are telling edit to do +to the entire buffer. +For example, +.DS I 1i +:\|\fBg/ /d +.R +72 less lines in file after global +.DE +will delete every line containing a blank anywhere in it. +This could adversely affect +your document, since most lines have spaces between words +and thus would be deleted. +After executing the global command, +edit will print a warning if the command added or deleted more than one line. +Fortunately, the undo command can reverse +the effects of a global command. +You should experiment with the global command +on a small file of text to see what it can do for you. +.SH +More about searching and substituting +.PP +In using slashes to identify a character string +that we want to search for or change, +we have always specified the exact characters. +There is a less tedious way to +repeat the same string of characters. +To change ``text'' to ``texts'' we may type either +.DS I 1i +:\|\fB/text/s/text/texts/ +.R +.DE +as we have done in the past, +or a somewhat abbreviated command: +.DS I 1i +:\|\fB/text/s//texts/ +.R +.DE +In this example, the characters to be changed +are not specified \- +there are no characters, not even a space, +between the two slash marks +that indicate what is to be changed. +This lack of characters between the slashes +is taken by the editor to mean +``use the characters we last searched for as the characters to be changed.'' +.PP +Similarly, the last context search may be repeated +by typing a pair of slashes with nothing between them: +.DS I 1i +:\|\fB/does/ +.R +It doesn't mean much here, but +:\|\fB// +.R +it does illustrate the editor. +.DE +(You should note that the search command found the characters ``does'' +in the word ``doesn't'' in the first search request.) +Because no characters are specified for the second search, +the editor scans the buffer for the next occurrence of the +characters ``does''. +.PP +Edit normally searches forward through the buffer, +wrapping around from the end of the buffer to the beginning, +until the specified character string is found. +If you want to search in the reverse direction, +use question marks (?) instead of slashes +to surround the characters you are searching for. +.PP +It is also possible +to repeat the last substitution +without having to retype the entire command. +An ampersand (&) used as a command +repeats the most recent substitute command, +using the same search and replacement patterns. +After altering the current line by typing +.DS I 1i +:\|\fBs/text/texts/ +.R +.DE +you type +.DS I 1i +:\|\fB/text/& +.R +.DE +or simply +.DS I 1i +:\|\fB//& +.R +.DE +to make the same change on the next line in the buffer +containing the characters ``text''. +.SH +Special characters +.PP +Two characters have special meanings when +used in specifying searches: ``$'' and ``^''. +``$'' is taken by the editor to mean ``end of the line'' +and is used to identify strings +that occur at the end of a line. +.DS I 1i +:\|\fBg/text.$/s//material./p +.R +.DE +tells the editor to search for all lines ending in ``text.'' +(and nothing else, not even a blank space), +to change each final ``text.'' to ``material.'', +and print the changed lines. +.PP +The symbol ``^'' indicates the beginning of a line. +Thus, +.DS I 1i +:\|\fBs/^/1. / +.R +.DE +instructs the editor to insert ``1.'' and a space at the beginning +of the current line. +.PP +The characters ``$'' and ``^'' have special meanings only in the context +of searching. +At other times, they are ordinary characters. +If you ever need to search for a character that has a special meaning, +you must indicate that the +character is to lose temporarily +its special significance by typing another special character, +the backslash (\\), before it. +.DS I 1i +:\|\fBs/\\\\\&$/dollar/ +.R +.DE +looks for the character ``$'' in the current +line and replaces it by the word ``dollar''. +Were it not for the backslash, the ``$'' would have represented +``the end of the line'' in your search +rather than the character ``$''. +The backslash retains its special significance +unless it is preceded by another backslash. +.SH +Issuing \s-2UNIX\s0 commands from the editor +.PP +After creating several files with the editor, +you may want to delete files +no longer useful to you or ask for a list of your files. +Removing and listing files are not functions of the editor, +and so they require the use of \s-2UNIX\s0 system commands +(also referred to as ``shell'' commands, as +``shell'' is the name of the program that processes \s-2UNIX\s0 commands). +You do not need to quit the editor to execute a \s-2UNIX\s0 command +as long as you indicate that it +is to be sent to the shell for execution. +To use the \s-2UNIX\s0 command +.B rm +to remove the file named ``junk'' type: +.DS I 1i +:\|\fB!rm junk +.R +! +: +.DE +The exclamation mark (!) +indicates that the rest of the line is to be processed as a shell command. +If the buffer contents have not been written since the last change, +a warning will be printed before the command is executed: +.DS I 1i +[No write since last change] +.DE +The editor prints a ``!'' when the command is completed. +Other tutorials describe useful features of the system, +of which an editor is only one part. +.SH +Filenames and file manipulation +.PP +Throughout each editing session, +edit keeps track of the name of the file being edited as the +.I "current filename." +Edit remembers as the current filename the name given +when you entered the editor. +The current filename changes whenever the edit (e) command +is used to specify a new file. +Once edit has recorded a current filename, +it inserts that name into any command where a filename has been omitted. +If a write command does not specify a file, +edit, as we have seen, supplies the current filename. +If you are editing a file named ``draft3'' having 283 lines in it, +you can have the editor write onto a different file +by including its name in the write command: +.DS I 1i +:\fB\|w chapter3 +.R +"chapter3" [new file] 283 lines, 8698 characters +.DE +The current filename remembered by the editor +.I +will not be changed as a result of the write command. +.R +Thus, if the next write command +does not specify a name, +edit will write onto the current file (``draft3'') +and not onto the file ``chapter3''. +.SH +The file (f) command +.PP +To ask for the current filename, type +.B file +(or +.B f ). +In response, the editor provides current information about the buffer, +including the filename, your current position, the number of +lines in the buffer, +and the percent of the distance through the file +your current location is. +.DS I 1i +:\|\fBf +.R +"text" [Modified] line 3 of 4 --75%-- +.DE +.\"The expression ``[Edited]'' indicates that the buffer contains +.\"either the editor's copy of the existing file ``text'' +.\"or a file which you are just now creating. +If the contents of the buffer have changed +since the last time the file was written, +the editor will tell you that the file has been ``[Modified]''. +After you save the changes by writing onto a disk file, +the buffer will no longer be considered modified: +.DS I 1i +:\|\fBw +.R +"text" 4 lines, 88 characters +:\|\fBf +.R +"text" line 3 of 4 --75%-- +.DE +.SH +Reading additional files (r) +.PP +The +\f3read (r)\f1 command allows you to add the contents of a file +to the buffer +at a specified location, +essentially copying new lines +between two existing lines. +To use it, specify the line after which the new text will be placed, +the \f3read (r)\f1 command, +and then the name of the file. +If you have a file named ``example'', the command +.DS I 1i +:\|\fB$r example +.R +"example" 18 lines, 473 characters +.DE +reads the file ``example'' +and adds it to the buffer after the last line. +The current filename is not changed by the read command. +.SH +Writing parts of the buffer +.PP +The +.B +write (w) +.R +command can write all or part of the buffer +to a file you specify. +We are already familiar with +writing the entire contents of the +buffer to a disk file. +To write only part of the buffer onto a file, +indicate the beginning and ending lines before the write command, +for example +.DS I 1i +:\|\fB45,$w ending +.R +.DE +Here all lines from 45 through the end of the buffer +are written onto the file named +.I ending. +The lines remain in the buffer +as part of the document you are editing, +and you may continue to edit the entire buffer. +Your original file is unaffected +by your command to write part of the buffer +to another file. +Edit still remembers whether you have saved changes to the buffer +in your original file or not. +.SH +Recovering files +.PP +Although it does not happen very often, +there are times \s-2UNIX\s+2 stops working +because of some malfunction. +This situation is known as a \fIcrash\fR. +Under most circumstances, +edit's crash recovery feature +is able to save work to within a few lines of changes +before a crash (or an accidental phone hang up). +If you lose the contents of an editing buffer in a system crash, +you will normally receive mail when you login that gives +the name of the recovered file. +To recover the file, +enter the editor and type the command +.B recover +(\fBrec\fR), +followed by the name of the lost file. +For example, +to recover the buffer for an edit session +involving the file ``chap6'', the command is: +.DS I 1i +.R +:\|\fBrecover chap6 +.R +.DE +Recover is sometimes unable to save the entire buffer successfully, +so always check the contents of the saved buffer carefully +before writing it back onto the original file. +For best results, +write the buffer to a new file temporarily +so you can examine it without risk to the original file. +Unfortunately, +you cannot use the recover command +to retrieve a file you removed +using the shell command \f3rm\f1. +.SH +Other recovery techniques +.PP +If something goes wrong when you are using the editor, +it may be possible to save your work by using the command +.B preserve +(\fBpre\fR), +which saves the buffer as if the system had crashed. +If you are writing a file and you get the message +``Quota exceeded'', you have tried to use more disk storage +than is allotted to your account. +.I +Proceed with caution +.R +because it is likely that only a part +of the editor's buffer is now present in the file you tried to write. +In this case you should use the shell escape from the editor (!) +to remove some files you don't need and try to write +the file again. +If this is not possible and you cannot find someone to help you, +enter the command +.DS I 1i +:\|\fBpreserve +.R +.DE +and wait for the reply, +.DS I 1i +File preserved. +.DE +If you do not receive this reply, +seek help immediately. +Do not simply leave the editor. +If you do, the buffer will be lost, +and you may not be able to save your file. +If the reply is ``File preserved.'' +you can leave the editor +(or logout) +to remedy the situation. +After a preserve, you can use the recover command +once the problem has been corrected, +or the \fB\-r\fR option of the edit command +if you leave the editor and want to return. +.PP +If you make an undesirable change to the buffer +and type a write command before discovering your mistake, +the modified version will replace any previous version of the file. +Should you ever lose a good version of a document in this way, +do not panic and leave the editor. +As long as you stay in the editor, +the contents of the buffer remain accessible. +Depending on the nature of the problem, +it may be possible +to restore the buffer to a more complete +state with the undo command. +After fixing the damaged buffer, you can again write the file +to disk. +.SH +Further reading and other information +.PP +Edit is an editor designed for beginning and casual users. +It is actually a version of a more powerful editor called +.I ex. +These lessons are intended to introduce you to the editor +and its more commonly-used commands. +We have not covered all of the editor's commands, +but a selection of commands +that should be sufficient to accomplish most of your editing tasks. +You can find out more about the editor in the +.I +Ex Reference Manual, +.R +which is applicable to both +.I ex +and +.I edit. +One way to become familiar with the manual is to begin by reading +the description of commands that you already know. +.bd I 3 +.SH +Using +.I ex +.fl +.bd I +.PP +As you become more experienced with using the editor, +you may still find that edit continues to meet your needs. +However, should you become interested in using +.I ex, +it is easy to switch. +To begin an editing session with +.I ex, +use the name +.B ex +in your command instead of +.B edit. +.PP +Edit commands also work in +.I ex, +but the editing environment is somewhat different. +You should be aware of a few differences +between +.I ex +and +.I edit. +In edit, only the characters ``^'', ``$'', and ``\\'' have +special meanings in searching the buffer +or indicating characters to be changed by a substitute command. +Several additional characters have special +meanings in ex, as described in the +.I +Ex Reference Manual. +.R +Another feature of the edit environment prevents users from +accidently entering two alternative modes of editing, +.I open +and +.I visual, +in which +the editor behaves quite differently from normal command mode. +If you are using ex and you encounter strange behavior, +you may have accidently entered open mode by typing ``o''. +Type the \s-2ESC\s0 key and then a ``Q'' +to get out of open or visual mode and back into +the regular editor command mode. +The document +.I +An Introduction to Display Editing with Vi\|\| +.R +provide full details of visual mode. +.bp +.SH +.ce 1 +\s+2Index\s0 +.LP +.sp 2 +.2C +.nf +addressing, \fIsee\fR line numbers +ampersand, 20 +append mode, 6-7 +append (a) command, 6, 7, 9 +``At end of file'' (message), 18 +backslash (\\), 21 +buffer, 3 +caret (^), 10, 20 +change (c) command, 18 +command mode, 5-6 +``Command not found'' (message), 6 +context search, 10-12, 19-21 +control characters (``^'' notation), 10 +control-H, 7 +copy (co) command, 15 +corrections, 7, 16 +current filename, 21 +current line (\|.\|), 11, 17 +delete (d) command, 15-16 +dial-up, 5 +disk, 3 +documentation, 3, 23 +dollar ($), 10, 11, 17, 20-21 +dot (\f3\|.\|\f1) 11, 17 +edit (text editor), 3, 5, 23 +edit (e) command, 5, 9, 14 +editing commands: +.in +.25i +append (a), 6, 7, 9 +change (c), 18 +copy (co), 15 +delete (d), 15-16 +edit (text editor), 3, 5, 23 +edit (e), 5, 9, 14 +file (f), 21-22 +global (g), 19 +move (m), 14-15 +number (nu), 11 +preserve (pre), 22-23 +print (p), 10 +quit (q), 8, 13 +read (r), 22 +recover (rec), 22, 23 +substitute (s), 11-12, 19, 20 +undo (u), 16-17, 23 +write (w), 8, 13, 21, 22 +z, 12-13 +! (shell escape), 21 +$=, 17 ++, 17 +\-, 17 +//, 12, 20 +??, 20 +\&., 11, 17 +\&.=, 11, 17 +.in -.25i +entering text, 3, 6-7 +erasing +.in +.25i +characters (^H), 7 +lines (@), 7 +.in -.25i +error corrections, 7, 16 +ex (text editor), 23 +\fIEx Reference Manual\fR, 23 +exclamation (!), 21 +file, 3 +file (f) command, 21-22 +file recovery, 22-23 +filename, 3, 21 +global (g) command, 19 +input mode, 6-7 +Interrupt (message), 9 +line numbers, \fIsee also\fR current line +.in +.25i +dollar sign ($), 10, 11, 17 +dot (\|.\|), 11, 17 +relative (+ and \-), 17 +.in -.25i +list, 10 +logging in, 4-6 +logging out, 8 +``Login incorrect'' (message), 5 +minus (\-), 17 +move (m) command, 14-15 +``Negative address\(emfirst buffer line is 1'' (message), 18 +``No current filename'' (message), 8 +``No such file or directory'' (message), 5, 6 +``No write since last change'' (message), 21 +non-printing characters, 10 +``Nonzero address required'' (message), 18 +``Not an editor command'' (message), 6 +``Not that many lines in buffer'' (message), 18 +number (nu) command, 11 +password, 5 +period (\|.\|), 11, 17 +plus (+), 17 +preserve (pre) command, 22-23 +print (p) command, 10 +program, 3 +prompts +.in .25i +% (\s-2UNIX\s0), 5 +: (edit), 5, 6, 7 +\0 (append), 7 +.in -.25i +question (?), 20 +quit (q) command, 8, 13 +read (r) command, 22 +recover (rec) command, 22, 23 +recovery, \fIsee\fR\| file recovery +references, 3, 23 +remove (rm) command, 21, 22 +reverse command effects (undo), 16-17, 23 +searching, 10-12, 19-21 +shell, 21 +shell escape (!), 21 +slash (/), 11-12, 20 +special characters (^, $, \\), 10, 11, 17, 20-21 +substitute (s) command, 11-12, 19, 20 +terminals, 4-5 +text input mode, 7 +undo (u) command, 16-17, 23 +\s-1UNIX\s0, 3 +write (w) command, 8, 13, 21, 22 +z command, 12-13 + |