|SAFE Commands||DANGEROUS Commands||SHORTCUT Keystrokes|
ANSI.SYS is a device driver that needs to be loaded when your computer starts up. It controls the display of fonts and colors, controls cursor movement, reassigns the functions of keys, and allows you to use ANSI escape sequences as embedded meta-commands within batch files to add color, change video modes, place text precisely on the screen, etc. For more detailed help on ANSI.SYS, type HELP ANSI.SYS at any DOS command prompt.
To activate ANSI.SYS you need to put a line in your CONFIG.SYS file, which resides in the DOS boot directory or root directory of your PC that tells your PC to load the driver whenever it is booted or turned on. (In Windows 95 you'll find CONFIG.SYS in the C:\WINDOWS\COMMAND directory) Use one of the two following lines to activate the driver:
The first statement loads ANSI.SYS into conventional memory, the second loads ANSI.SYS into high memory. Load the driver into high memory to save space for programs or drivers that require conventional memory.
NOTE: Unless you need the features provided by ANSI.SYS, don't load it. It will take up memory unnecessarily and could interfere with some other programs. If your PC is running Windows 95, for example, you don't need ANSI.SYS.
APPEND allows a program to open data files in any directory on your PC as if the files were in the same directory as the one from which the program was started. NOTE: Don't use APPEND with Windows programs or from a DOS shell from Windows, it will crash your system. Appended directories are treated by the DOS system as if they were part of the current directory.
ASCII (American Standard Computer Information Interchange) code is used almost universally in PCs to display and control the placement of text on the screen and to provide a set of special characters for use in computer commands. Basically, a single ASCII code consists of 8 bits (8 on/off pulses - bits), 7 for data and 1 for parity. The 8 bit length allows for a total of 256 ASCII characters, including the standard alphabetic and numerical characters as well as a number of special signs, symbols and international characters. The table below provides a correspondence between ASCII designation and the character generated by the code.
ASCII Code Chart
(Characters displayed will depend on the font loaded)
The ATTRIB command can be used to display or alter file characteristics. Files can be:
A batch file is a flat ASCII file - a text file - that contains a list of DOS commands. It must have the standard .BAT filename extension. A batch file can be executed by typing its name (with or without the .BAT filename extension) at the DOS command prompt. It is good policy to create a directory on your PC called C:\BAT which contains all the batch files you create yourself. The C:\BAT directory needs to be placed in the PATH= statement in your AUTOEXEC.BAT file so that DOS can find your batch files and execute them from a command entered at any location on your PC within the directory tree. When you enter the name of a batch file at the DOS command prompt, the commands contained within the batch file are executed in the order given and control is returned to DOS upon completion.
You can use any DOS command in a batch file that you could also use at the DOS command prompt. In addition, there are some DOS commands that were designed especially with use in batch files in mind:
The BREAK command sets or clears extended CTRL+C (break) checking. The command functions at the DOS command prompt or as a command line in the CONFIG.SYS file. Including the BREAK ON command in the CONFIG.SYS file extends checking every time the computer is booted or turned on. The CTRL+C keystroke combination is used to interrupt a program or an activity and is generally only read from the keyboard during input/output operations such as printing, screen display or interaction with the keyboard. Turning BREAK to the ON status allows DOS to extend CTRL+C interrupt checking to more kinds of activities. This is useful in that it gives the CTRC+C interrupt more power. The default is set to OFF. Only two forms of command syntax are acceptable:
The BUFFER command is used within the CONFIG.SYS file to allocate memory for a specified number of buffers when the computer is booted or starts.
The CALL command is used within a batch command file to start up another batch command file. CALL returns control to the original batch command file on successful completion of the called routines.
The CHDIR, or CD command displays the name of the current directory or changes the current directory.
The CHKDSK command is largely obsolete and has been replaced in its functionality by the SCANDISK.EXE program. CHKDSK checks the status of a physical disk and displays a status report. It is used to fix disk errors such as lost data strings and file allocation table errors. It also displays a brief summary of disk usage.
CHOICE is used only in batch command files to prompt the user to make a choice among several displayed options. CHOICE displays a prompt with options and pauses until the user chooses from among the set of displayed options. The batch command file branches to labeled subsections depending on the choice made.
COMMAND and COMMAND.COM
The COMMAND.COM program invokes the DOS command interpreter. For all intents and purposes, it is the DOS system. Issuing the COMMAND command (sic) at a system prompt or from within a batch command file starts a new instance of the command interpreter.
The CONFIG.SYS file is an important system file that must reside in your DOS root directory. It contains parameters and commands that set up the environment in which your computer works. It also initializes any special devices that your system requires and determines the way in which your computer will utilize memory.
The CONFIG.SYS file and its contents can be complex. For more information on the file, see your DOS manual.
A template for a minimal CONFIG.SYS file is displayed below:
DEVICE=C:\DOS\ANSI.SYS DEVICE=C:\DOS\HIMEM.SYS DEVICE=C:\DOS\EMM386.EXE DOS=HIGH,UMB BUFFERS=20 FILES=40 BREAK ON
The COPY command copies one or more files to a location or file specified. The COPY command can also be used to concatenate files. When more than one file is copied, DOS displays the name of each file specified as it is copied.
See also the related command MOVE.
This command can be used to change the input devices that control and drive your computer, normally the keyboard, and the mouse or joystick. If control is attached to another device, such as a serial port, the computer can be controlled remotely, perhaps via modem.
The DATE command calls up a dialog that allows you to specify the date held in the computers nonvolatile memory. If the date your computer is assigning to files is incorrect this command allows you to correct the date parameter.
This is a driver system that was used to double the disk storage space in computers prior to DOS 6.22 by compressing stored data. It has been replaced by the DRVSPACE system.
Runs the Debug program - a testing and editing tool. DEBUG [[drive:][path]filename [testfile-parameters]]
[drive:][path]filename Specifies the file you want to test. testfile-parameters Specifies command-line information required by the file you want to test.After Debug starts, type ? to display a list of debugging commands.
The DEFRAG program can be run interactively or in command mode from a batch file with command switches set. The program scans the directory structure and file allocation tables and optimizes the file structure of the disk specified. Your machine's performance will be enhanced by periodic use of the DEFRAG program to clean up and reorganize your hard disk. This program cannot be run from Windows.
DEL - ERASE
The DEL command deletes or erases a specified file or object from the disk. A full path to the file to be deleted can be included.
This command will remove a specified directory and all its subdirectories from the disk. WARNING: This command is difficult to reverse or recover from if used incorrectly or inadvertently. Use it with extreme caution.
DEVICE and DEVICEHIGH
Used only in the CONFIG.SYS file, this command loads a specified device driver into conventional memory when the computer is booted or started up. Device drivers power your PC's peripherals and set up the DOS environment. The corresponding DEVICEHIGH command loads the specified device driver into high memory. This allows other device drivers or programs more room in conventional memory.
The DIR command displays the files and subdirectories present in a specified directory on a specified drive.
This command permits the user to compare the contents of two floppy diskettes for differences track by track based on the format and organization of the first diskette in the comparison.
This command copies the entire content of a source floppy diskette to a target floppy diskette track by track based on the formatting of the source floppy and overwrites any information on the target floppy.
This system driver allows the system to display international character sets on most color monitors. The driver must be loaded within the CONFIG.SYS file.
See also the discussion on International Commands.
This command is used only in the CONFIG.SYS file. It governs where the operating system is loaded into memory and how it maintains its links to memory while running programs.
This command can be input from the keyboard at a system prompt but is usually invoked
from the AUTOEXEC.BAT startup file. It loads a keystroke memory program
which allows the user to recall previously issued commands with the up arrow on the
keypad and edit them so that they can be repeated or modified and reentered with different
parameters. The program requires about 3K of conventional memory and remains resident. It
is of a type referred to as TSR (Terminate and Stay
Ready or Terminate and Stay Resident).
Reinstalls a new copy of the program in memory even if it's already been loaded.
Specifies the size of the buffer the program uses to store previous commands. The default is 512 bytes.
Displays all macros associated with DOSKEY.
Display a history of all commands stored in the buffer and can be redirected to a file for processing as a batch command file.
Starts the program so that commands can be edited in overstrike or insert mode. The default is overstrike. Insert is more useful.
Creates a command macro with name macroname and commands command_text.
This disk driver system must be installed within the CONFIG.SYS file. It creates a logical drive on the hard disk that can be used in the place of a physical floppy disk drive.
This command must be placed in the CONFIG.SYS file. It defines parameters for physical devices such as disk and tape drives when the operating system starts up. It modifies the characteristics of an existing disk drive and is used to override the driver definitions for any previously set up block device.
DRVSPACE and DRVSPACE.SYS
This utility can be used to compress data storage on the hard disk or floppies using the DRVSPACE.SYS system driver with must be installed in the CONFIG.SYS file. Nowadays, most high-end PCs have enough disk space to make the use of this compression system thoroughly unnecessary.
This command is used primarily in batch command files as a means to enable or disable command echoing to the screen. The only command parameters are:
Echoing can be turned on or off (enabled or disabled). A text message can be echoed to the screen from a batch command file. If this is coupled with ANSI codes, color, style and placement of text on the screen can be manipulated.
The ECHO OFF command can, itself, be hidden from view from within a batch command file by using the following form:
This command invokes the DOS screen editor.
This system driver saves and restores the screen display when the DOS Shell Task Swapper is used with simple EGA monitors. If your computer system has an EGA monitor this driver must be installed within the command in the CONFIG.SYS file.
The expanded memory system, EMM386.SYS, gives your computer access to the upper memory area, beyond the conventional 640K, that all microcomputers still use. It is generally used in combination with the HIMEM.SYS driver.
EMM386.SYS allows the computer to use it's hard disk drive as extended memory to simulate expanded memory. It also allows you to load programs and other system drivers into upper memory blocks (UMB).
EMM386.SYS is a device driver and must be loaded when the PC boots up or is started using the DEVICE command in the CONFIG.SYS file. Only microcomputers with an 80386 microprocessor, or better, can use EMM386.SYS.
See your DOS users manual for command syntax and parameters.
See the DEL command.
This command expands a compressed program file. It can be used to retrieve and expand compressed program files from the DOS setup diskettes.
This command, used by itself, gives a condensed list of all available DOS commands. If used in conjunction with a command name it provides a shortened version of the help available on that subject. See also HELP.
This command can be invoked in the AUTOEXEC.BAT or installed in the CONFIG.SYS file. It helps the system to open frequently used files more rapidly. For more information on the complex command parameters enter HELP FASTOPEN and any command prompt. FASTOPEN cannot be run from Windows.
This command is used to compare the contents of two files for similarities and differences.
This command is used only in the CONFIG.SYS file. It specifies the number of file control blocks (FCBS) that the operating system can have open at one time. A file control block is a data storage area that contains information about a file and its characteristics.
This commmand starts the FDISK program. This program is used to configure the hard disk for use with DOS. It can be used to display and alter hard disk configuration, including add, delete and reconfigure hard disk partitions.
WARNING: The FDISK program must be used with extreme caution since it exercises great control over the structure and functionality of the hard disk.
You can request FDISK to display current hard disk parameters by using the FDISK /STATUS. This command is basically harmless, as it is only informational in character and does not really invoke the full FDISK capability.
This command is used only in the CONFIG.SYS file. It specifies the number of files that can be opened at one time. The maximum value is 255.
The FIND command searches for a specified text string in a file or group of files. When the search is complete the program displays any lines of text that contained strings that matched the specified search text.
This command begins a batch command file loop. It will execute a set of batch file commands repeatedly until a condition set by a variable is met.
The FORMAT command prepares a disk for use with the DOS system. Unformatted disks cannot be read or written to by the system.
The command creates a root directory and establishes an empty file allocation table FAT for the directory structure. It checks the disk for bad sectors and marks them so that they cannot be used by the system.
WARNING: The FORMAT command is destructive. It will destroy all data on a disk which has been formatted and used previously. This is very difficult to recover from or undo without the appropriate disk utilities. Use FORMAT with caution.
The UNFORMAT command can be used to recover from an accidental diskette format, with some difficulty, but only if the /U optional switch has not been used and previous formatting information has been saved.
This command is used exclusively in batch command files to allow the batch process to branch to a specified location, usually dependent on some sort of conditional test.
This command loads a memory-resident program that allows the system to dump screen displays to the printer. It can only be used if the system has a CGA color monitor or better.
This command invokes the DOS help facility and files. It can be used alone - which calls up the full screen version of the facility with index - or it can be used in combination with the command for which help is need - which calls up only that command's information screens.
This system driver manages extended memory and is generally loaded as a companion to EMM386.SYS. It coordinates the use of extended memory, including the high memory area (HMA), so that no applications or device drivers attempt to use the same memory areas at the same time.
The INCLUDE command is used exclusively in the CONFIG.SYS file for defining multiple boot configurations. Multiple boot configurations require that a menu be defined within the CONFIG.SYS file which appears when the computer boots or starts up. Every menu item displayed corresponds to a block of commands called a configuration block, in the CONFIG.SYS file.
The INSTALL command is used exclusively in the CONFIG.SYS file to install system components and programs.
INTERLNK and INTERSRVR
This program connects two computers through their respective parallel or serial ports and enables them to share disk drives and printer ports. The INTERLNK.EXE device driver must be INSTALLed (above) in the CONFIG.SYS file before the command can be used.
The related INTERSRVR command also needs to be installed in the CONFIG.SYS file. This program starts the INTERLNK server that permits the two machines to communicate with one another.
The following commands are used to change country-specific settings and character sets within the CONFIG.SYS file:
CHCP - COUNTRY - KEYB - NLSFUNC
Your PC is already set up for standard American English functionality of you purchased it within the United States or Canada.
See also the DISPLAY.SYS driver.
The command is issued from any system prompt and is used to change the volume label for the current disk or diskette.
EXAMPLE: LABEL BOOT_DISK
Used exclusively within the CONFIG.SYS file this command specifies the maximum number of drives that can be accessed depending on the drive letters assigned.
The LH command is used only in the CONFIG.SYS file. It loads a program into the upper memory area. Loading a program into the upper memory area preserves conventional memory for other programs.
This command is used as a prefix when loading programs. It forces the program's memory stack to be loaded above the first 64K of conventional memory. This ensures that the program will not POKE any commands into memory reserved for the operating system.
This command displays the amount of used and free memory on the system. It can be used to display information about allocated memory areas, free memory areas, and programs that are currently loaded into memory.
This command starts the DOS MemMaker program, which optimizes the computer's memory by moving device drivers and memory-resident programs to upper memory. To use MemMaker, the computer must have an 80386 or 80486 processor and extended memory. The program reboots the computer and tests a variety of memory configurations for optimal performance. It modifies system files AUTOEXEC.BAT and CONFIG.SYS which set up the system environment whenever the computer is booted or started.
MENUCOLOR - MENUDEFAULT - MENUITEM
These commands are used exclusively in the CONFIG.SYS file. They set up the colors used by the menu system defined in the file, the default conditions used by the menu system and the menu items displayed in the menu system.
The MD command creates a directory or subdirectory on the specified disk and in the specified location within the existing directory tree.
See also the related directory commands:
The MODE command is used to configure a variety of system devices. It can perform many different tasks, such as displaying system status, changing system settings, and reconfiguring or reassigning system ports and devices.
Because the MODE command performs so many different functions, the form of the command needed to carry out each task is quite different. Below is a list of tasks for which the command can be used:
The MORE command displays ouptut from a file one screen at a time with prompting for additional screens of information.
This command moves one or more files from one specified location to another. The command can also be used to rename directories by "moving" them.
The MSAV command calls up a program that will scan the computer's hard disk or floppies for known viruses. The trouble is that there are new viruses springing up all the time. The program cannot protect against viruses that it does not know how to detect. It can clean those it does find off your system.
The MSBACKUP program allows you to specify which of the files and directories on your computer system you would like to back up to floppy diskettes or other storage devices. It is good policy to back up your computer once shortly after it has been set up and is running well and to save this initial backup in a safe place against the day it is needed. It is also good policy to perform incremental backups on a regular basis so that newer files and directories are saved, as well.
This is a program that can be loaded interactively from the keyboard or from within the AUTOEXEC.BAT file. The program uses the parameters supplied to locate and initialize any CDROM devices that are installed on your computer so that they can be used by the system. Generally, it is started from the AUTOEXEC.BAT file. The correct driver for your particular CDROM device must be properly installed in the CONFIG.SYS file.
The MicroSoft Diagnostic program MSD is used to check your system for configuration and operational errors. The program can be launched either from your AUTOEXEC.BAT file or from the keyboard interactively. Based on the switches set, the program can produce detailed reports on a number of system parameters and settings.
This function controls whether or not the NumLock key on the keyboard's numeric keypad is set to ON or OFF when the computer is booted or started. This can be set only in the CONFIG.SYS file.
The PATH statement can be issued either from the keyboard interactively or from within the AUTOEXEC.BAT file so that it is executed each time the computer is booted or started. The PATH statement determines which directories the system searches when it is asked to load or run a program or system file. Excessively long PATH statements used to be a problem on older machines because they limited the amount of environment space available to the system, but this is less of a problem on the newer, more powerful machines.
This statement is used only in batch command files. It causes the execution of the command file to stop and displays a message prompting the user to press a key to continue. This is generally used to allow users to have sufficient time to read menu options or displayed text.
This command turns the power conservation system on and off and configures it. The power management system reports the status of power management, and sets levels of power conservation for your computer. The system is governed by the POWER.EXE program which needs to be installed in the CONFIG.SYS file.
This command is used to send information contained within a data file to the system printer. The command can operate in the background since it creates a printer queue. Although the basic command is very simple:
where filename is the name of the file to be printed, there is also a great deal of complexity and variety of forms of output that can be invoked using a number of special switches and command parameters.
This command can change the appearance of the system command prompt. The command prompt can be customized to display any text desired, including such information as the name of the current directory. This is a very helpful means of identifying your place in the directory tree at any given time.
This system driver can use part of the computer's random access memory (RAM) to act in the place of a physical hard disk drive. The driver must be loaded in the CONFIG.SYS file so that it is mounted when the system starts or is booted. A RAMDRIVE can greatly increase the speed of some often repeated disk read/write operations and can be configured as the default for these operations.
This command removes (deletes) a directory or subdirectory from the system's file allocation table and physically from the specified drive. The directory must be emptied of files beforehand.
See the related command MKDIR.
This command is used in system files and batch command files to "remark out" lines or to insert remarks into such files. The system takes no action on a command line that is preceded with the REM command.
The REN command is used to rename a file or files. The command cannot be used to move files or to rename files across drives. If the destination name is already in use the command fails.
This command is used to replace files in a target directory with file in a source directory that have the same names. The command can also be used to add unique filenames to the target directory.
This is a command provided for backward compatibility with any older version of DOS. The command invokes the restore utility which can recover files from information backed up to floppy diskettes.
It has been replaced with the MSBACKUP program.
This command invokes the DOS ScanDisk software. This software system can be used to analyze the hard disk or floppies for errors and can be configured to correct or report on any errors it finds. It is good policy to use the ScanDisk utility periodically to keep the computer's hard disk in top condition. A well-organized and groomed hard disk improves the overall performance of your microcomputer.
This command is used to set system variables and set up system parameters within the AUTOEXEC.BAT file and batch command files.
SETVER and SETVER.EXE
This command is used to display the DOS version table. It can report a version number for versions earlier than 6.0 to programs or device drivers that are incompatible with higher versions of DOS and require earlier versions to function properly. Even setting the version may not be enough to get some older programs to function in newer versions of DOS. It may be necessary for you to keep and use boot diskettes for older versions.
The SETVER.EXE program must be loaded in the CONFIG.SYS file if downward compatibility to older versions is desired at every boot or start up.
This command is generally included in the AUTOEXEC.BAT file. It starts the SHARE program which monitors file sharing and dynamic locking and allocation capabilities on all disks and networked drives. This disallows simultaneous access to the same file by programs which might otherwise engage in a tug-of-war over the file or overwrite each other's changes to the file and destroy your work. The program can become annoying in some Windows applications which refuse to release control of files even when finished with them.
This command must be executed within the CONFIG.SYS file. It specifies the name and location of any alternate command interpreter to be used in the place of the standard COMMAND.COM. This is useful in some instances where alternate command interpreters purchased to provide additional system security are desired.
This command is used exclusively within batch command files. It shifts the order of replaceable parameters %0 through %9. This can be useful for executing a number of commands as a group.
This command starts and can be used to configure the SMARTDrive software which creates and manages the disk cache used for extended memory. Although it can be invoked at the command prompt, the program is generally run from within the AUTOEXEC.BAT file so that it intitalizes at every boot and start up.
This command reads the specified input file, sorts the data according to the supplied parameters and writes the results to either the screen, a file or to another output device, like a printer. Sorting can be done in ascending or descending order.
The DOS sort program is rather primitive in its capabilities. Many programs incorporate data sort features which you can use in place of this utility.
This command must be included within the CONFIG.SYS file. It supports dynamic use of data stacks which handle system hardware interrupts - control codes that devices use to gain access to the system. The command parameters allow the user to specify the number of stacks to be used and the size in bytes of each stack.
This command must be included within the CONFIG.SYS file. It defines an item to be included on a startup menu which, when selected, calls up another set of choices within the submenu chosen. The command is used to customize multiple configuration command menus.
The command is used to alias or substitute a path with a virtual drive through a drive letter. The command can be issued from the keyboard interactively or from within a command file. The drive letter assigned as an alias is a virtual drive. It can be used to substitute for the specified path as if it were a real physical drive. The command cannot be used from within Windows.
Used only from within the CONFIG.SYS file, this command specifies special command switch options:
This command is used to transfer the DOS operating system files to another disk. It copies the critical system files to the new disk or diskette.
FORM and EXAMPLE: SYS A: - transfers the system to drive A:
WARNING: This command can be issued from a commmand prompt on a floppy diskette which has been formatted to be bootable and contains the SYS.COM command file. If this is done it can overwrite the hard disk's operating system files. This can cause irreparable damage to the disk if the operating system versions are not the same.
The TREE command is used to generate a hierarchical listing of all the directories on the specified drive. This is a very useful way to view the entire directory structure of a disk. Below is a partial example of what the display looks like:
This command displays the contents of a text file on the screen or on another output device. Output can be piped to a file, as well.
FORM and EXAMPLE: TYPE MYFILE.TXT - displays the specified file on the screen.
The command can be used with the MORE command to paginate output and prompt the user for continued viewing.
This command can be used to restore files which were previously erased or deleted but only if it is used before the file areas allocated to the erased files have not already been overwritten by data from other, newer files.
This command can be used to restore a disk which has been accidentally formatted. This can only be done if the diskette or disk has not been formatted unconditionally, in which case, critical unformatting information has not been saved. The command can only be used to restore local hard disks or floppy disks. It will not work on networked drives. The command can also be used to refresh or rebuild a corrupted file allocation table on a hard disk drive.
WARNING: This command can destroy all the data on your hard disk if it is used improperly.
This command is generally set in the AUTOEXEC.BAT file. It directs the system to verify that all files are written correctly to disk and displays the status of verification for every file written. The command can also be issued at the system prompt. The verify function greatly slows down disk access and should be used judiciously.
This command invokes the VSafe memory resident virus checking program which monitors all file and disk activity for virus transfers. It is generally executed at startup from within the AUTOEXEC.BAT file. The program continuously monitors the system for viruses and displays warning messages when any are detected. It requires about 22K of conventional memory.
This command is stronger than the related COPY command. It copies whole directories, associated subdirectories and all files within them except for hidden and system files to the specified target. This is much simpler and more powerfule than the simple COPY command, but it is also potentially much more dangerous and needs to be used with some caution.
Most high-end PCs today have enough disk space and power to permit multiple boot configurations. They can even accomodate several operating systems on the same hard disk in different disk partitions. DOS, itself, can be set up with multiple configurations each of which is specifically designed to meet some specific need. Commonly, multiple configurations are used to set up radically different memory parameters often required by multimedia software programs which can conflict with one another for critical system resources. It may be necessary for you to set up a boot configuration for each one. This can become tedious.
All multiple configuration options are stored in the CONFIG.SYS file along with all the parameters necessary to establish a boot menu which gives the user a choice among several configuration options.
Safe DOS CommandsHere is a list of DOS commands that under almost all circumstances are completely safe to use anywhere, anytime and can't do anything to hurt your computer system or your existing files and directories:
Dangerous DOS CommandsHere is a list of DOS commands that should be used with caution under some or all circumstances since they can damage or modify your existing files and directories or significantly modify system parameters so that the computer won't work properly any more. Some can produce changes that are either irreversible or are very difficult to recover from without a good system backup:
Keystrokes and Keystroke Combinations
Some or all of the common keystrokes and keystroke combinations listed in the table below, along with their functions, will work either in DOS, itself, or in programs which are running under the DOS system. Some keystrokes will perform slightly different functions depending on the application that is being run. Some applications will completely reassign keystrokes. If this is the case, the user manual will generally provide a table showing keystroke equivalents and functions. Keystroke combinations are shown in the following manner:
This means that you must hold down the control key the alternate function key and the delete key in succession and then let go of all the keys to perform the function - in this case - a warm boot (Don't do this now, please!).