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Chapter 3 - The Command Line Discussion of the command line and prompt, entering and executing commands, changing system disks, how ConIX processes arguments, and special requests to the command line processor. - CONTENTS - __________________________________________________________________ 3. The Command Line...................................... 3-1 3.1 The System Prompt................................. 3-1 3.2 Changing the Default Directory.................... 3-1 3.3 The Warm Boot..................................... 3-2 3.3.1 Warm Boot Density Change....................... 3-3 3.4 Command Line Editing.............................. 3-4 3.5 Entering Commands................................. 3-6 3.6 Executing a Program in Memory (!)................. 3-7 3.7 Aborting Command Execution........................ 3-8 3.8 Multiple Commands Per Line........................ 3-8 3.9 Command Arguments................................. 3-9 3.10 Backslash (Non-Interpret) Character............... 3-10 3.11 Forced Case Mapping............................... 3-11 3.12 Control Characters................................ 3-12 3.13 Data Type Conversions............................. 3-13 - i - ConIX Operating System The Command Line 3. The Command Line A major portion of the ConIX Operating System is devoted to the processing of user commands. These commands are generally entered at the system prompt and form the command line. The Command Line Processor is the part of the operating system that takes the command line, breaks it up into different segments, and analyzes it. The power of ConIX lies, for the most part, in its enormous flexibility with regard to manipulating the command line. Exactly how this is done, and what features are available to the user, is described in the sections that follow. 3.1 The System Prompt When ConIX is ready to process a command, it displays a prompt on the console screen in the form: <d:##> where the single letter d indicates the currently selected disk drive (A-P) and the two-digit number ## indicates the currently selected user area (00-31). For example, the prompt displayed when using drive A, user area 0 is: <A:00> and will be used to indicate the system prompt in examples throughout this manual. If the currently selected disk is write protected by the operating system (the drive set to Read Only), the `:' in the prompt will be changed to a `!', e.g.: <A!00> This will most often occur if you swap disks without resetting the drive. CP/M detects the change and does not allow you write to the new disk. To return the drive to normal use, simply hit CTRL-C at the prompt level. Under ConIX, diskettes need not contain a CP/M image on the operating system tracks. Note that the prompt change does not take place immediately after you swap disks. The R/O setting is activated only after the disk directory has been accessed by a program. For example, if you ran the DIR (list directory) command after the swap, the next prompt would indicate the write-protected status. 3.2 Changing the Default Directory Whenever you cold load CP/M into your system after a reset or power-up, you are automatically placed into the default directory of drive A, user area 0. It is from this directory that all .COM programs will be loaded, unless you specify otherwise. 3-1 The Command Line ConIX Operating System When ConIX is initially loaded, the default directory which was set from CP/M will be maintained. This default may be changed at any time by specifying a new directory, as: <A:00> (D:)(#/) where D is the disk directory (A-P), and # is the user area (0- 31). Either or both may be supplied, and the default directory and prompt will be changed accordingly. All future commands and files will then be loaded from the new directory unless respecified. In addition, there exists a method of changing the default directory only for the execution of a single command. The syntax of this feature is: <A:00> @(D:)(#/) <command> (arg(s)) which executes the command as if it were requested from the specified disk and/or user area. For example, <A:00> stat foo.asm will execute the Digital Research STAT command on the file FOO.ASM stored in the current directory, namely drive A, user area 0. If you wished to STAT a file in a user area and/or disk other than the current default, you couldn't supply a user area with the filename since CP/M does not support this. Instead, you must manually change to the desired directory and then execute STAT from there. Or, more conveniently, you can type: <A:00> @B:10/ stat foo.asm which will execute the STAT command from the directory of drive B:, user area 10 and return you to the default directory which was previously set. This is exactly equivalent to typing: <A:00> b:10/ <B:10> stat foo.asm . . STAT runs on the file FOO.ASM in B:10 . <B:10> a:0/ <A:00> where you had to manually specify the desired directory changes before and after the STAT command was executed. 3.3 The Warm Boot There are two kinds of boots (short for bootstrap) under the CP/M environment: they are the Cold Boot and the Warm Boot. Your system does a cold boot the first time CP/M is loaded. By cold we mean that there is no software in memory to perform operating 3-2 ConIX Operating System The Command Line system functions. Once loaded, a signon message is printed and control is passed to the CP/M CCP. The warm boot occurs while the operating system is resident in memory. It has two primary purposes. The first is to reset the disk system, returning all disks to a writable state. This is most often done at the prompt level by hitting a CTRL-C after you change disks. The second function performs a complete reload of CP/M and the CCP from system tracks of the A: disk. This operation differs from a cold boot, as there still remains some software in memory to do the reload, namely the BIOS, which contains the system-dependent routines. A warm boot most often occurs after a large disk-based command program finishes execution. It is really only necessary for the purpose of reloading CP/M, since such programs generally overwrite the CCP with their stack and data areas. When working under CP/M, you will notice when a warm boot occurs if there is an increased delay after a program finishes execution, and before the prompt is displayed. Some programs do not cause this delay because they do not require much memory and, therefore, do not have to overwrite the CCP. Under ConIX, this warm boot delay is often eliminated entirely, as ConIX usually remains in memory while programs execute. A jump to location zero or SysCall #0 never enters the BIOS, as this function is handled within ConIX itself. Hitting a CTRL-C at the ConIX prompt will cause a reset of the write-protect setting of all disks without performing a CP/M or ConIX reload, thereby eliminating much of the usual delay. This should be done whenever you change disks, otherwise you will not be allowed to modify the data stored on the new disk. 3.3.1 Warm Boot Density Change Some computers may use the warm boot operation to allow you to load different densities of disks into the system. If this is true, the media-type cannot be changed since ConIX will not supply the warm boot that is sometimes used by the BIOS to reset the density settings and disk parameter configurations. The program WARMBT.COM has been supplied on your distribution diskette for the purpose of performing a BIOS Warm Boot directly from ConIX. To execute a warm boot, simply type: <A:00> warmbt which will cause ConIX to store its current environment (option settings, etc.) on disk, and then exit to CP/M via a standard warm boot operation. A command-submit file will have been created which will cause ConIX to be reloaded along with its saved 3-3 The Command Line ConIX Operating System environment. This complex operation is performed exclusively by a ConIX Command Language program, the source code to which has been provided on the Distribution Diskette for your examination. In addition, WARMBT will accept command line arguments in the form: <A:00> warmbt <command> . . . where the given command(s) will be executed after control is returned to CP/M, and before ConIX is reloaded. This provides a mechanism for executing programs in the resident operating system without intervention by ConIX. For example, the command line: <A:00> warmbt "dir *.com" stat will exit to CP/M, list all files whose names end with .COM, print available disk space, and return to ConIX. NOTE: in instances when we will mention a warm boot in this manual, we refer only to the process by which a program's execution is terminated. This does not mean that an actual CP/M and BIOS warm boot operation will take place. No CP/M reload can ever take place when a program exits via a warm boot under ConIX. It is for this reason that diskettes used with ConIX need not contain a CP/M image on the operating system tracks unless, of course, an exit to CP/M will be necessary. 3.4 Command Line Editing ConIX supports the standard line editing functions available when entering commands or other line input (via BDOS syscall 10). The editing process has been somewhat refined in operation and also contains some new additions. Valid commands are: CTRL-B: Boot Program When this control character is typed at the first character position after the system prompt, a predetermined program will be booted into memory. By default, the command MENU will be executed, to facilitate the quick loading of a specialized user-friendly menu program, if available. The value of the CTRL-B key can be redefined using the OPT +/-BC internal command to load and execute any program of your choice. CTRL-C: Warm Boot If this control sequence is entered at the first character position of an input line, a warm boot will take place. If this was done while entering data into a running program, execution 3-4 ConIX Operating System The Command Line will be terminated and control returned to ConIX. Otherwise, if typed at the system prompt level, all disks will be reset to a writable state. CTRL-E: Next Line This sequence is used to advance the cursor to the beginning of the next physical input line. You may then continue entering data from that point. This function only modifies the screen and does not affect the actual input data. It is useful for terminals or printers which do not auto-wrap when the cursor goes past the end of a line. CTRL-H: Backspace Use this sequence to backspace on the input line and delete the character preceding the current cursor position. The character to be removed will be overwritten by a space or blank, thus causing it to be erased from the screen. CTRL-I: Tab The tab character will advance the cursor to the next screen tab stop, which is preset to every eight characters. Although spaces will be displayed so as to move the cursor, the ASCII tab character (07h) will still remain in the line. CTRL-J: Line Feed CTRL-M: Carriage Return Either of these characters will terminate the input line, sending it to ConIX or the running program for processing. CTRL-O: Restore Line This sequence will recall the previously entered input line as stored in the input line buffer. Therefore, if the previous line may be re-used with few or no changes, you may recall it without having to retype it. Characters deleted by CTRL-H or CTRL-X can also be restored by using CTRL-O. CTRL-P: Transcript Mode ON/OFF Entering this sequence once will enable Printer Transcript Mode, which will cause all characters displayed on the console screen to be simultaneously printed on the printer (LST) device. Entering this character again will disable this feature. In other words, it has an on/off toggling action. CTRL-R: Recall Line The current contents of the input line will be reprinted on the screen when this sequence is typed. It is a form of screen refresh, which will display the input line as it has been entered thus far. 3-5 The Command Line ConIX Operating System CTRL-U: Cancel Line This function deletes all previously typed characters from the input line buffer. The deleted characters will remain on the screen, and the cursor will advance to the next line. CTRL-X: Erase Line When this control sequence is entered, all input which had been displayed on the screen will be deleted, and the input will, once again, start from the beginning of the line. The characters displayed on the screen will be overwritten with backspaces and, thus, physically erased as well. CTRL-\: Non-Interpret Assigning control sequences to editing functions has caused these characters to be excluded from direct entry as data on the input line. If any special editing characters are to be entered, use the CTRL-\ sequence followed by the desired character. This character will then be displayed on the screen and stored as input without being interpreted by ConIX. To enter the non-interpret sequence itself, simply type it twice. DEL (7F hex): Delete Character DEL is used to delete the last typed character from the input line. The affected character will be echoed to the screen as an indication of its erasure. This function is best suited for editing on a terminal or printer that cannot backspace. 3.5 Entering Commands When the ConIX prompt is displayed, commands may be entered in the same way as when CP/M was being used. For example: <A:00> dir . . displays the directory . <A:00> era foo.asm . . erases FOO.ASM . <A:00> ed foo.asm . . invokes an editor on FOO.ASM . <A:00> As with CP/M, all characters entered onto the command line in lower case are mapped to upper case before execution. If a command is built into ConIX, it is run immediately (as are DIR and ERA). A command which is not internal (as ED) is searched for on 3-6 ConIX Operating System The Command Line disk with a .COM ending (as ED.COM). 3.6 Executing a Program in Memory (!) ConIX contains a special command which allows you to execute a program stored in system memory as if it were loaded from a .COM file. The syntax of this command is: <A:00> !(&address) (arg(s)) where address is the location in memory at which the program resides. The args list is a group of filenames or other data which may be supplied to the program on the command line for its execution. All data areas and parameters will be set in the same manner as when executing commands from disk. Thus we can think of the ! command as causing the disk loading process to be bypassed entirely. If address is not specified, a default location of 100 hex is assumed. This address is most significant as it is the beginning of the Transient Program Area (TPA) in memory. Since all .COM programs are loaded into memory starting at this address, they can be re-executed directly from memory without having to be reloaded from disk. Take, for example, the STAT program, supplied by Digital Research with CP/M. If you wanted to determine the size of a file, you would type: <A:00> stat foo.asm STAT.COM would be loaded from disk and executed, reporting the number of Kbytes occupied by FOO.ASM on disk. Let's say you then wanted to determine the size of another file. You could re-run STAT in the same way as before, except with a different filename, or, you could type: <A:00> ! foo.com which would execute STAT directly from memory with the new argument, FOO.COM. The reason this is possible is that all .COM still remain in memory after execution. Therefore, the ! command skips the loading process and executes the program already stored in memory. There are a few things that you should be aware of when using this feature. Firstly, some programs modify their code and/or data areas while running in memory and, therefore, may not re-execute properly. Secondly, ConIX has no way of telling whether garbage or an actual program resides in the memory you specify. Therefore, be sure that there really is a program in memory before you instruct ConIX to run it. The system may hang if invalid instructions are executed. If used properly, this command could really save quite a bit of time. 3-7 The Command Line ConIX Operating System 3.7 Aborting Command Execution If you enter a command at the prompt level and then realize that you do not want to run it, you may abort its execution by using any of a number of different methods described below. If you specified a disk-based command (.COM) program, you can easily cancel the request before execution begins by simply entering the CTRL-X sequence. You can tell if the command has not yet begun to execute if the cursor is still sitting on top of the `<' of the `<A:00>' prompt. In other words, the Line Feed character has not yet been printed. At this point, ConIX is in the process of loading the program into memory from the disk file, and the command can be aborted before it starts to execute. However, once execution begins, it becomes somewhat more difficult to cancel. It is unfortunate that, on most systems, there exists no convenient method of interrupting a program once invoked by the user. CP/M sometimes allows you to abort a program if it is currently outputting to the screen. You may be able to stop the output with a CTRL-S and then enter a CTRL-C which will cause a warm boot to take place. However, if a program is disk-bound, there is no way it can be stopped other than by forcing a BDOS error message by pulling out the disk from the drive (aargh!), or performing a cold system reset. With ConIX, as in CP/M, typing CTRL-S will temporarily stop screen (CON) output and CTRL-C can be used to abort execution. In addition, ConIX provides a feature called Disk Wait Control which allows you to use a CTRL-S to pause execution when a program is accessing a disk. Once paused, you may similarly abort using CTRL-C, or continue running the program by typing any other character. The only type program which cannot be stopped is one which is performing some in-memory calculation since it would be impossible for ConIX to intervene. 3.8 Multiple Commands Per Line More than one command may be entered on a single command line by simply separating each command and its arguments (if any) with a semicolon, as: <A:00> dir; era foo.asm; ed foo.asm which runs the commands in sequence from left to right, just as if you would have typed each command on a separate command line. Any spaces before or after the semicolon are optional. This is very useful if you have some time consuming commands to run in sequence and don't really want to wait around for each one to finish before starting the next. 3-8 ConIX Operating System The Command Line 3.9 Command Arguments Most commands can be invoked with arguments, which are words passed to the program that tells it something about what you want done. A program can either request data from the user while it's running, through interactive prompts or questions, or it could take the needed information from the command line arguments. The latter method is the route most programs take if all they require is, say, a filename, as is the case with: <A:00> ed foo.asm where FOO.ASM is ED's command line argument. This is also the case with most of the ConIX internal commands which gather their operational data from the command line. ConIX and CP/M differentiate between separate arguments by the space or tab you type between them. For example, COMPARE may be a user-supplied program which compares two files, as: <A:00> compare <file1> <file2> where the contents of file1 and file2 are compared to each other. The user may issue the command: <A:00> compare foo.asm foo.sav where FOO.ASM is the first argument, and FOO.SAV is the second argument to the program COMPARE. Any spaces or tabs between the arguments or after the command name will be truncated to a single space. It is often useful to combine multiple words into one argument without having the spaces between them act as separators to break them up. Take, for example, the internal command ECHO, which is a utility that prints its arguments, as: <A:00> echo Welcome to ConIX! WELCOME TO CONIX! <A:00> Notice how the spaces (or tabs) were truncated to a single space and the lowercase letters were mapped to uppercase. In this example, the total number of arguments to the ECHO command is three. If, however, you were to enclose the arguments in double quotes, you'd get: <A:00> echo " Welcome to ConIX!" Welcome to ConIX! <A:00> You can see that the spaces were included and the characters were not mapped to uppercase. In this instance, there is only one argument which contains the entire string of three words and spaces. 3-9 The Command Line ConIX Operating System In effect, the double quotes tell ConIX not to change the case of letters or interpret the meaning of any separation characters within them. So far, you've been introduced to the space, tab, and semicolon as separator characters. There are others which you will come across as you read on. If you place nothing within a double quote string, then what you get is called the Null Argument. It occupies space on the command line as an argument, however, it consists of only one character, a NUL, which is the same as a CTRL-@ or 00 hex. 3.10 Backslash (Non-Interpret) Character One of the most powerful characters, so to speak, is the backslash, `\'. It removes any special meaning that the character following it may have to ConIX, and puts it onto the command line just like another character. For example, if you want to place a double quote within a quoted argument string, you can precede it with a backslash as: <A:00> echo "\" Welcome to ConIX!\"" " Welcome to ConIX!" <A:00> If you forgot to enter the backslashes, you'd get five arguments. The first a null, the second WELCOME, the third TO, the fourth CONIX!, and the fifth another null argument. As you may suspect, the backslash can also be used in many other instances as well. For example: <A:00> echo Welcome\ \ to\ \ C\o\nIX! WELCOME TO ConIX! <A:00> The backslashes before the spaces between the words serve to join them together to form one argument. The backslash tells the Command Line Processor to ignore the special meaning of the space characters, namely, to separate arguments. Thus, the spaces are treated as any other character and are included within the argument. The backslash before the o and n of ConIX! causes these characters to be entered onto the command line in the same case as they were typed. In this instance, the mapping of lowercase characters to uppercase is suppressed. You can even use the backslash itself as a character on the command line. Simply backslash the backslash (meaning, don't interpret the non-interpret character) as: <A:00> echo "Here is a Backslash \\ Character" Here is a Backslash \ Character <A:00> 3-10 ConIX Operating System The Command Line 3.11 Forced Case Mapping As we have shown in previous examples, characters entered on the command line are normally mapped to uppercase, unless they are preceded by a backslash or enclosed in double quotes. Forced Case Mapping is a feature which can even cause the mapping of characters within double quotes. It is implemented by using: _L to map all characters to lowercase _U to map all characters to uppercase _N do not map any characters __ to return to standard case mapping For example, `_L' (underscore followed by the letter ell) is used as: <A:00> echo _lHello "There" hello there <A:00> where all characters in lowercase remained untouched, but characters in uppercase were mapped to lowercase. By definition, the `_L' caused all characters following it to be mapped to lowercase, even those in double quotes. Similarly, using `_U' yields the opposite result, as: <A:00> echo _uHello "There" HELLO THERE <A:00> where all characters were force-mapped to uppercase. If no mapping is desired, use `_N' as: <A:00> echo _nHello There Hello There <A:00> where all characters remain in the same case as they were typed. This is operationally equivalent to using OPT -UC before the command and OPT +UC after it (as described later). By using `__' (two underscores), the standard case mapping can be returned to its default setting, as: <A:00> echo _uHello "There" __Hello "There" HELLO THERE HELLO There <A:00> The `_U' converted all characters until the `__' to uppercase, and after the `__', regular case mapping was invoked, returning the case privileges of the double quotes. 3-11 The Command Line ConIX Operating System 3.12 Control Characters ConIX will not allow you to use the CTRL key to enter actual control characters onto the command line. These characters are generally non-printable, and are sometimes used to modify certain terminal characteristics. In most instances they can be considered undesirable glitch, and may actually interfere with program operation. It is for this reason that they are normally stripped from the command line. Control characters span the range of NUL (00 hex) to US (1F hex). One such character is a CTRL-L, which clears the screen on most terminals. This sequence is entered by holding down the <CTRL> key with one finger while pressing the `L' key with another. If you entered this sequence on the command line, you'd see: <A:00> ^L ConIX types the `^' before the `L' to represent the entry of the CTRL-L character sequence. If you entered a CTRL-L as an argument to ECHO, you'd get: <A:00> echo ^L <A:00> which will not clear the screen, but print just a blank line. Why? Because ConIX strips off all control characters from the command line. It is as if you hadn't typed the control character at all. But we shall not ban them totally, for there are instances when you would want them to be there. There are a few methods that can be used to include control characters on the command line. You could enter the control sequence in double quotes, as: <A:00> echo "^L" because the quotes allow control characters within them. Or, you could prefix the control sequence with a backslash: <A:00> echo \^L because backslash removes any special meaning given by ConIX to the character following it. There is also a special character, the circumflex or up-arrow, which can be used to represent a control sequence, without actually using the CTRL key. This two-character sequence appears on the screen to be almost identical to entering the actual control character. Instead, you spell it out manually as: <A:00> echo ^l 3-12 ConIX Operating System The Command Line where you type a `^' followed by an `l' (ell), as opposed to the two-stroke CTRL-L code. This sequence will be changed into the single control character code it represents. It is especially useful in command files where, if the actual character would appear inside it, the screen would clear when you TYPE or list the file. Also, some editors don't allow entry of control characters. Another special character is available which will change the normal operation of ConIX to remove all control characters from the command line. This is done with the tilde or squiggle character, where: <A:00> ~echo ^L . . . screen clears <A:00> which allows a control character sequence to be included anywhere on the command line. Using a second tilde would reset ConIX to strip off control chars for the remainder of the line or until another tilde. In other words, the tilde has a toggling on/off action. For example: <A:00> echo ~^L~ ^A^B^C~ ^G . . . screen clears and terminal beeps <A:00> causes only the first CTRL-L and last CTRL-G to be accepted. The first tilde turns control characters on, the second off, and the third back on again. Note that using the tilde will not affect the other methods of enabling entry of control characters (i.e. "", \, ^). 3.13 Data Type Conversions Many built-in functions require data to be entered in the form of hexadecimal or decimal numbers. For convenience, you may specify such a number in either hex or decimal format as: &<hexnum> where hexnum is a hexadecimal number from 0-FFFF hex, or, #<decnum> where decnum is a decimal number from 0-65535. In addition, you may specify a number as its ASCII character equivalent, as: '<char> which will cause the specified char to be converted into its numeric value and then passed to the command. Wherever commands are listed as requiring numeric arguments, we will use certain conventions for describing the default data type 3-13 The Command Line ConIX Operating System that command or function is expecting. If an `&' is indicated, the default data type is hexadecimal. If a `#' is indicated, the default data type is decimal. In each case, the number may be entered in the default type without specifying its corresponding type character. Only when a non-default number is entered must it be preceded by its special type character. To illustrate, take for example the EXAM command which examines memory. It is defined as: EXAM <&start> <&end> where start and end are, by default, two hexadecimal numbers describing the start and end addresses. If you wished to examine memory between 00 and FF hex, you'd type: <A:00> exam 0 ff or, if you speak only decimal, you can type: <A:00> exam #0 #255 which would produce operationally equivalent results. ConIX internally performs these conversions automatically. Similarly, the SUM command will add two numbers, as: SUM <#num1> <#num2> where num1 and num2 are, by default, two decimal numbers. If you wished to add 10 and 15, you'd type: <A:00> sum 10 15 or, if you wanted to sum two hex numbers, just type: <A:00> sum &a &f You can also mix hex and decimal numbers as: <A:00> sum &a 15 Additionally, you can use an ASCII character as: <A:00> sum '^j 15 Each of these examples would produce the decimal result of 25. Note that the data types given in the arguments do not affect the data type of the result. SUM will always print a decimal result, regardless of whether it was given hex or decimal numbers as arguments. You can convert results to decimal or hex by capturing the command's output using redirection and then passing the data to the BDEC or DECB internal commands. This process will be described clearly in later sections. 3-14 "CHAPTER1DOC τCHAPTER2DOC `(CHAPTER3DOC