HELP command output from RT-11SJ displayed on a VT100.
HELP commandIn computing, help is a command in various command line shells such as COMMAND.COM , cmd.exe , Bash, qshell, 4DOS/4NT, Windows PowerShell, Singularity shell, Python, MATLAB [1] and GNU Octave. [2] It provides online information about available commands and the shell environment. [3]
help command for DCL on RSX-11 
help commandThe command is available in operating systems such as Multics, [4] Heath Company HDOS, [5] CP/M Plus, DOS, IBM OS/2, [6] eComStation, ArcaOS, IBM i, [7] Microsoft Windows, ReactOS, [8] THEOS/OASIS, [9] Zilog Z80-RIO, [10] Microware OS-9, [11] Stratus OpenVOS, [12] HP MPE/iX, [13] Motorola VERSAdos, [14] KolibriOS [15] and also in the DEC RT-11, [16] RSX-11, [17] TOPS-10 [18] and TOPS-20 [19] operating systems. Furthermore it is available in the open source MS-DOS emulator DOSBox and in the EFI shell. [20]
On Unix, the command is part of the Source Code Control System and prints help information for the SCCS commands.
The Multics help command prints descriptions of system commands/active functions and subroutines. It also prints various information about the system status, system changes, and other general information. This information is selected from segments maintained online, which are in a special format, called information segments. More than 800 information segments are available. [21]
The DEC OS/8 CCL help command prints information on specified OS/8 programs. [22]
The help command is available in MS-DOS 5.x and later versions of the software. [23] The help command with a 'command' parameter would give help on a specific command. If no arguments are provided, the command lists the contents of DOSHELP.HLP.
In MS-DOS 6.x this command exists as FASTHELP.
The MS-DOS 6.xx help command uses QBasic to view a quickhelp HELP.HLP file, which contains more extensive information on the commands, with some hyperlinking etc. The MS-DOS 6.22 help system is included on Windows 9x CD-ROM versions as well.
In PC DOS 5 and 6 help is the same form as MS-DOS 5 help command.
PC DOS 7.xx help uses view.exe to open OS/2 style INF files (cmdref.inf, dosrexx.inf and doserror.inf), opening these to the appropriate pages.
The Software Link's PC-MOS includes an implementation of help. [24] Like the rest of the operating system, it is licensed under the GPL v3. [25]
In DR-DOS, help is a batch file that launches DR-DOS' internal help program, dosbook.
Datalight ROM-DOS includes an implementation of the help command. [26] ROM-DOS was introduced in 1989 as an MS-DOS compatible operating system designed for embedded systems.
The 4DOS/4NT help command uses a text user interface to display the online help.
help command outputUsed without parameters, help lists and briefly describes every system command. Windows NT-based versions use MS-DOS 5 style help. Versions before Windows Vista also have a Windows help file (NTCMDS.HLP or NTCMDS.INF) in a similar style to MS-DOS 6.
In PowerShell, help is a short form (implemented as a PowerShell function) for access to the Get-Help Cmdlet.
Windows PowerShell includes an extensive, console-based help system, reminiscent of man pages in Unix. The help topics include help for cmdlets, providers, and concepts in PowerShell.
In Bash, the builtin command help' [28] lists all Bash builtin commands if used without arguments. Otherwise, it prints a brief summary of a command. Its syntax is:
help [-dms] [pattern]
HELP is a DCL utility that contains information on the use of commands and descriptions of some OpenVMS concepts such as time formats and lexical functions, as well as lists of commands for a particular purpose (HELP Hints).
The command-syntax is:
help [command]
Arguments:
command This command-line argument specifies the name of the command about which information is to be displayed.Z:\>help If you want a list of all supported commands type help /all .A short list of the most often used commands:<DIR > Directory View. <CD > Display/changes the current directory. <CLS > Clear screen. <COPY >Copy files. ...>>> helpType help() for interactive help, or help(object) for help about object.>>> help()Welcome to Python 2.5! This is the online help utility.If this is your first time using Python, you should definitely check outthe tutorial on the Internet at https://www.python.org/doc/tut/.Enter the name of any module, keyword, or topic to get help on writingPython programs and using Python modules. To quit this help utility andreturn to the interpreter, just type "quit"....octave-3.0.0.exe:1> help Help is available for the topics listed below. Additional help for built-in functions and operators is available in the on-line version of the manual. Use the command `doc <topic>' to search the manual index. ... 
In computing, dir (directory) is a command in various computer operating systems used for computer file and directory listing. It is one of the basic commands to help navigate the file system. The command is usually implemented as an internal command in the command-line interpreter (shell). On some systems, a more graphical representation of the directory structure can be displayed using the tree command.
The mkdir command in the Unix, DOS, DR FlexOS, IBM OS/2, Microsoft Windows, and ReactOS operating systems is used to make a new directory. It is also available in the EFI shell and in the PHP scripting language. In DOS, OS/2, Windows and ReactOS, the command is often abbreviated to md.
In Unix-like and some other operating systems, the pwd command writes the full pathname of the current working directory to the standard output.
An environment variable is a user-definable value that can affect the way running processes will behave on a computer. Environment variables are part of the environment in which a process runs. For example, a running process can query the value of the TEMP environment variable to discover a suitable location to store temporary files, or the HOME or USERPROFILE variable to find the directory structure owned by the user running the process.
fdisk is a command-line utility for disk partitioning. It has been part of DOS, DR FlexOS, IBM OS/2, and early versions of Microsoft Windows, as well as certain ports of FreeBSD, NetBSD, OpenBSD, DragonFly BSD and macOS for compatibility reasons. Windows 2000 and its successors have replaced fdisk with a more advanced tool called diskpart.
In computing, echo is a command that outputs the strings that are passed to it as arguments. It is a command available in various operating system shells and typically used in shell scripts and batch files to output status text to the screen or a computer file, or as a source part of a pipeline.
In computing, XCOPY is a command used on IBM PC DOS, MS-DOS, IBM OS/2, Microsoft Windows, FreeDOS, ReactOS, and related operating systems for copying multiple files or entire directory trees from one directory to another and for copying files across a network.
In computing, exit is a command used in many operating system command-line shells and scripting languages.
In computing, tree is a recursive directory listing command or program that produces a depth-indented listing of files. Originating in PC- and MS-DOS, it is found in Digital Research FlexOS, IBM/Toshiba 4690 OS, PTS-DOS, FreeDOS, IBM OS/2, Microsoft Windows, and ReactOS. A version for Unix and Unix-like systems is also available.
In computing, ATTRIB is a command in Intel ISIS-II, DOS, IBM OS/2, Microsoft Windows and ReactOS that allows the user to change various characteristics, or "attributes" of a computer file or directory. The command is also available in the EFI shell.
In computing, ren is a command in various command-line interpreters (shells) such as COMMAND.COM, cmd.exe, 4DOS, 4NT and Windows PowerShell. It is used to rename computer files and in some implementations also directories. It is analogous to the Unix mv command. However, unlike mv, ren cannot be used to move files, as a new directory for the destination file may not be used. Alternatively, move may be used if available. On versions of MS-DOS that do not support the move command, the user would simply copy the file to a new destination, and then delete the original file. A notable exception to this rule is DOSBox, in which ren may be used to move a file, since move is not supported.
In computing, del is a command in command-line interpreters (shells) such as COMMAND.COM, cmd.exe, 4DOS, NDOS, 4OS2, 4NT and Windows PowerShell. It is used to delete one or more files or directories from a file system.
In computing, find is a command in the command-line interpreters (shells) of a number of operating systems. It is used to search for a specific text string in a file or files. The command sends the specified lines to the standard output device.
In computing, copy is a command in various operating systems. The command copies computer files from one directory to another.
In computing, format, a command-line utility that carries out disk formatting. It is a component of various operating systems, including 86-DOS, MS-DOS, IBM PC DOS and OS/2, Microsoft Windows and ReactOS.
In computing, choice is a command that allows for batch files to prompt the user to select one item from a set of single-character choices. It is available in a number of operating system command-line shells.
A command-line interface (CLI) is a means of interacting with a computer program by inputting lines of text called command-lines. Command-line interfaces emerged in the mid-1960s, on computer terminals, as a user-friendly alternative to punched cards.
In computing, diskcopy is a command used on a number of operating systems for copying the complete contents of a diskette to another diskette.
In computing, diskcomp is a command used for comparing the complete contents of a floppy disk to another one.
The command-line tool exe2bin is a post-compilation utility program available on MS-DOS and other operating systems.
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