Ian & Stuart's Australian Mac 1

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Text File | 1994-09-20 | 20KB | 404 lines

2 The Environment The Macintosh Finder allows you to perform a series of operations by clicking and dragging icons and windows with your mouse, while MacDOS expects you to type commands on the keyboard. MacDOS does not normally display a cursor changing from a clock to an arrow to tell you when an operation has been completed. Instead, whenever MacDOS completes the execution of a command and is ready to accept the next one, it displays a prompting string at the beginning of the bottom line of the screen. That line is called Command Line. With commands affecting several files and folders at a time, MacDOS also displays the name of each item before it begins operating on it. A command is like an order in English: a verb in the imperative form, possibly followed by one or more objects and some qualifiers. Commands are usually case insensitive. The verb is called Command Name, the objects Parameters, and the qualifiers Switches or Options. After completing the typing of the command, you direct MacDOS to start its execution by pressing the RETURN key. Command Name The command name must be the first word of the command and is never case sensitive. Also, command names provided by MacDOS never contain spaces or other special characters. Parameters Most commands need one or more parameters to identify the objects they are requested to operate on. An example of commands which do not require any additional information is CLS, used to clear the MacDOS window. Many commands accept different numbers of parameters and automatically "fill in" the missing parameters with default values. For example, the command DIR displays lists of files in the MacDOS window and expects one parameter which identifies the files to be listed. Nevertheless, you can just type DIR without parameters to list the contents of the current folder. Parameters are sometimes case sensitive. For example, when you rename a file you have to type the new name exactly as you want it, with upper and lower case characters. The order of parameters is almost always fixed. For example, if you want to rename a file, you have to type the old name first and the new name second. A case in which the order is not important is when you copy several files with a single COPY command. In that case, you type the filenames one after the other separated by commata. MacDOS will copy the files in the order in which you specify them, but this should usually have no practical consequences. Switches Switches always start with a slash (the character '/'). This is how MacDOS distinguishes them from parameters. The slash is always followed by a character which identifies the particular switch, and possibly other characters which select different ways of operation. For example, you obtain a sorted list of files by adding the switch /O to the command DIR. You can also specify ways of sorting by adding other characters to the switch: DIR/ODS displays a list of files sorted on the basis of their last upDate and Size (update first), while DIR/OSD lists the same files but giving priority to their size rather than the date and time of last update. As switches are always used to request optional features, they are never mandatory. Nevertheless, very often you will need to use one or more switches. For example, to avoid that a long list of files disappears off the top of the MacDOS window, you can type DIR/P instead of simply DIR. As with parameters, switches are seldom case sensitive. One case sensitive switch is /T, used to select a file-type. The 'T' of the switch can be in lower or upper case, but the file type must be correct: /t=TEXT is different from /t=TeXT because the two types 'TEXT' and 'TeXT' are seen as different by the Mac Operating System. The order and position of switches within a command are in most cases irrelevant. In fact, MacDOS extracts and analyses all the switches before looking at the parameters. One switch accepted by all commands is /?. When you type this switch in any position, MacDOS ignores all other parameters and switches and displays a brief description of the command. Redirection and Piping Most commands produce some output messages, either because that is their purpose, or because they provide information on their progress. For example, the purpose of the command DIR is precisely to produce a list of filenames. On the other hand, the COPY command lists the names of the files being copied. By default, MacDOS displays these messages in the MacDOS window but you can decide to re-direct them to a text file. To do so, you must add to the command a "greater than" character followed by the name of the text file. For example, DIR>MyFile lists the contents of the current folder in the text file MyFile rather than on the screen. When you redirect the output, MacDOS produces files which can be directly opened with any text editor or word processor. Note that error and warning messages are never redirected to files. MacDOS always displays them on the screen. Also, if you attempt to redirect the output of commands which have nothing to redirect, MacDOS displays a warning message, ignores the redirection, and executes the command as if you had not attempted a redirection. You can append the output of a command to an existing file, rather than create a new one, by typing two "greater than" signs instead of one (eg. DIR>>MyFile). The commands which accept output redirection are: ALARM, CALL, CD, CHDIR, CLOSE, CONFIRM, COPY, DATE, DIR, EJECT, EXIT, HELP, LOG, MD, MKDIR, MEM, MORE, NEXT, ONERROR, OPEN, PATH, PRINT, PROMPT, READ, RD, REM, REN, RENAME, RESTART, RMDIR, SERIAL, SHOW, SHUTDOWN, SUBSTVOL, TIME, TREE, TYPE, VER, VERIFY, VOL, WRITE, XCOPY . Some of these commands do not actually produce any output. Therefore, their acceptance of output redirection is simply an indication that they will not report a warning message if you do attempt to redirect their output. Beside redirecting the output produced by a command, you can also redirect the input from which the command MORE accepts data. You do this by appending to the command line a "less than" character followed by the name of the text file containing the data. This is useful in order to break down long displays into pages. For example, MORE<MyFile displays the text file MyFile one page at a time and prompts you to continue or interrupt the display at the end of each page. Input redirection is also possible with MacDOS extensions (ie. MacDOS filter applications). Please refer to the appropriate section for the details. Instead of redirecting the output of a command to a file and then use that file as input to MORE or to a filter application, you can combine the two commands and achieve the same result in a more efficient way. This mechanism is called piping. You just need to type the commands one after the other separated by a vertical bar (the character '|', called pipe). For example, if the on-line help displayed by the command COPY/? is too long to be contained in the MacDOS window, you can type COPY/?|MORE and MacDOS will wait for you at the end of each page. Pipes are only relevant for: • Internal commands which allow output redirection. • The command MORE (ie. the only internal command which accepts input redirection). • MacDOS filter applications. The command FOR is a special case, because it passes its output or input redirection to the command which follows the DO keyword. Therefore, although FOR itself does not accept redirection, a command line beginning with FOR can contain I/O redirection. Only single-line FORs accept I/O redirection. Moreover, input redirection and piping is only possible in conjuction with MORE . What follows is a complete list of the rules that govern redirection and piping in the MacDOS environment. In order to fully understand all its details, you will probably need to come back to this list after reading some other sections of this User's Guide. • In a single command, you can only redirect input and output once, and their order is irrelevant. If the line includes pipes, the input redirection applies to the first command and the output redirection to the last one, regardless of where the redirections actually appear within the line. • MacDOS displays a warning message whenever the user applies input or output redirection to a command that does not support it. • Most internal commands accept output redirection to file, but only MORE accepts input redirection. Single- line FORs accept input redirection when their DO is followed by MORE, in which case the redirection is considered to be referring to the MORE rather than to the FOR itself. Single-line FORs accept output redirection, but multi-line FORs don't. • Batch programs accept output redirection to file but not input redirection. • Applications and AppleScripts do not accept any I/O redirection. • MacDOS extensions accept both input and output redirections. Therefore, a chain of filters can obtain its input from a disk file rather than from a command. • MORE can only appear at the end of a command line (this includes the case in which there is nothing else and MORE is on its own). • A command line containing pipes can only begin with an internal command which supports output redirection (but excluding MORE), or with a filter. If it begins with a filter, the command line must include input redirection. • The command FOR only supports a pipe in the following case: FOR %var [/L] IN (set) DO internal-com-with-params | MORE That is, in the single-line format and with a single pipe used for MORE. Errors and Warnings MacDOS distinguishes between serious conditions which cause a command to be rejected or aborted (errors) and others which should not occur but can be tolerated (warnings). In any case, MacDOS displays a message to inform you that an abnormal condition has been detected. Most errors are due to the presence in a command of invalid parameters and switches, or the request to operate on something that does not exist. Warnings are usually caused by the attempt of redirecting I/O of a command which does not support redirection. You also get a warning when you attempt to use a DOS switch which is not supported by MacDOS. MacDOS normally reports errors and warnings by displaying a short message. You can use the ALARM ON command to have all error and warning conditions reported via an alert dialog box. MacDOS then pauses whenever it detects a problem and provides in the alert box some information which is not normally displayed. Refer to Appendix A for an indication of the possible causes of error and warning messages and some advice on possible remedies. Menus and Window The MacDOS window accepts commands and provides space for displaying command outputs. This is why throughout this manual it is also referred to as the console window. You can change the character size of the console window through the system variable FONTSIZE. MacDOS supports the standard mouse operations to work with text: cut, copy, paste, and clear. You can select text with the mouse and then select the appropriate item of the Edit menu or type the keyboard shortcut to perform the operation you need. This frees you from having to type long file and folder names, as you can copy names from a directory list and paste them into the command line. To make such an operation easier, MacDOS selects a whole quoted string (quote characters included) when you double click between a pair of matching quotes. Note that you cannot paste carriage return characters into the command line, because MacDOS interprets a carriage return as an order to execute a command. Typed characters are only accepted within the command line. If the selection is entirely outside the command line, the insertion point is moved to the end of the command line before showing the character typed. If, on the other hand, a selection covers part of a command, the selection is reduced to that part before replacing it with the character typed (ie. the left edge of the selection is moved to the first character of the command line). Only the command line can be altered. Therefore, outside of the command line: • "Cut Text" behaves like "Copy Text". • "Paste Text" moves to the end of the command line before pasting, effectively attaching the content of the clipboard to the end of the command. • "Clear Text" has no effect. If the selection includes a part of the command line, "Copy Text", "Paste Text", and "Clear Text" behave as if the selection only consisted of the part which is within the command line. That is, only the part of selection which is within the command line is cut, replaced, or cleared. Up and down arrows scroll through the previous and following commands. This possibility is particularly useful when you mistype a character of a long command, because you can "recall" the command by typing an up-arrow. You can then correct the mistake instead of having to retype the whole lot. Left and right arrows extend selections when they are shifted and move to the beginning and the end of the command line when they are pressed together with the option key. MacDOS also responds to the "Select cmd line" item of the Edit menu by highlighting and selecting whatever you have already typed after the current prompt. Similarly, "Select All" highlights the contents of the whole console window. The two items "Previous Cmd" and "Next Cmd" of the Edit menu (and their corresponding shortcuts cmd-dash and cmd- equal) behave like the up and down arrows. The console window accepts vertical scrolling and resizing via the standard vertical sidebar and boxes. The buffer is guaranteed to store at least the last 24000 characters typed or displayed. You can clear the console window with the command CLS (which stands for CLear Screen). To print the contents of the console window, select the "Print console..." item of the File menu or simply type the command PRINT . You can also set the format of the printed page by clicking on the item "Page Setup..." of the File menu. To close the console window and terminate MacDOS, you can: • Click on the "go away" box in the top left corner of the window. • Select either the Close or Quit item of the File menu. • Type cmd-Q. • Type the command EXIT . If you do not remember how to display MacDOS on-line help, select the "Help..." item of the apple menu. It will tell you how to use the command HELP . If some colleagues or friends would like to try MacDOS, you can create a demo version of MacDOS by selecting the "Make DEMO..." item of the File menu. MacDOS will then duplicate the MacDOS application file and disable the appropriate functionality. Control Codes You can abort the execution of most commands by typing cntl- C or cmd-dot. MacDOS achieves this by monitoring the keyboard at times when the current command can be safely interrupted. Two additional control codes are available: cntl-S and cntl- Q. They pause and resume long listings on the monitor screen. For example, instead of using the command MORE to list a text file one page at a time, you might choose to use the command TYPE and press cntl-S when you spot something which you want to read. You can then type cntl-Q to resume the listing or cntl-C to abort it. Tabbing You can use the TAB key to speed up the typing of long file and folder names and the shift-TAB key combination to enter frequently used strings. TAB When you press the TAB key, MacDOS interprets the preceding characters as a part of a file or folder name (with or without path) and attempts to complete it. To determine what portion of the command line to use, MacDOS examines the preceding characters in reversed order and stops when it finds a quote or a space. It then scans the current folder looking for matching names of files or subfolders: • If MacDOS does not find any match, it redisplays the command unchanged. • If MacDOS finds a single match, it completes the name within the command line and redisplays the command. • If MacDOS finds several matches, it lists them before redisplaying the command unchanged. In any case, MacDOS truncates the list of matches if it occupies more than half of the console window. If the matches have in common more characters than those typed by the user, MacDOS extends the partial name before redisplaying the command. This mechanism is particularly useful when navigating hierarchies of folders, because it lets you type the minimum number of characters needed to identify any particular item. Whenever MacDOS completes or extends a name and finds that the name was not quoted, it inserts the opening quote character. Shift-TAB When you type TAB while pressing the SHIFT key, MacDOS interprets the preceding characters as part of an abbreviation and attempts to replace it with a full string. For a description of this feature, please refer to the "Abbreviations" subsection of the "Customising MacDOS" section.