Help (command)
| Company type | Command-line utility |
|---|---|
| Industry | Computing / Software |
| Products | Online help for CLI shells |
In the realm of computing, the help command is utilized across numerous CLI shell environments, including but not limited to COMMAND.COM, cmd.exe, Bash, qshell, 4DOS/4NT, Windows PowerShell, Singularity shell, Python, MATLAB, and GNU Octave. This command offers users access to online guidance regarding the commands available and the shell’s operational context.
Implementations
The help command is integrated into a wide array of operating systems such as Multics, Heath Company’s HDOS, CP/M Plus, various versions of DOS, IBM’s OS/2, as well as its derivatives like eComStation and ArcaOS. It is also present in systems including IBM i, Microsoft Windows, the open-source project ReactOS, and proprietary platforms like THEOS/OASIS. Additionally, it appears in environments like the Zilog Z80-RIO, the Microware OS-9, Stratus Technologies’ OpenVOS, HP’s MPE/iX, Motorola VERSAdos, and KolibriOS. DEC operating systems such as RT-11, RSX-11, TOPS-10, and TOPS-20 also incorporate this command. Moreover, it is featured in the open-source MS-DOS emulator DOSBox as well as within the Unified Extensible Firmware Interface (EFI) shell.
Within Unix-based platforms, the help command is part of the Source Code Control System (SCCS), where it provides assistance related to SCCS commands.
Multics
On the Multics system, invoking help yields detailed descriptions of system commands, active functions, and various subroutines. It also presents information regarding system status and recent changes, drawing from an extensive repository of over 800 online information segments formatted specifically for this purpose.
DEC OS/8
The DEC operating system OS/8 features a help command within its Concise Command Language (CCL) that supplies details about designated OS/8 programs.
MS-DOS
Starting from version 5.x onward, MS-DOS includes the help command, which provides assistance on individual commands when supplied with arguments; if no parameter is given, it displays the contents of DOSHELP.HLP. In MS-DOS 6.x releases, this capability is delivered by the FASTHELP utility. The enhanced help interface in MS-DOS 6.xx employs QBasic to render the comprehensive HELP.HLP file featuring hyperlink navigation. This help system is also accessible via Windows 9x installation media.
PC DOS
Versions 5 and 6 of PC DOS include a help function paralleling that of MS-DOS 5. The PC DOS 7.xx iteration utilizes view.exe to open OS/2-style documentation files (cmdref.inf, dosrexx.inf, doserror.inf) directing users to appropriate reference sections.
PC-MOS
The operating system PC-MOS, developed by The Software Link, incorporates its own implementation of the help command. Both PC-MOS and its help functionality are distributed under the terms of the GPL v3 license.
DR-DOS
Within the DR-DOS environment, help is implemented as a batch script that triggers an internal help utility named dosbook.
ROM-DOS
Introduced by Datalight in 1989, ROM-DOS is an MS-DOS compatible platform designed for embedded applications and includes its own version of the help command.
FreeDOS
The FreeDOS project’s rendition of the help command was authored by Joe Cosentino.
4DOS/4NT
The help command in 4DOS/4NT delivers interactive assistance through a text user interface.
cmd.exe
When executed without arguments, help displays a list of system commands along with concise descriptions. Windows NT-based editions adopt the MS-DOS 5 style help format; earlier versions prior to Windows Vista feature a Windows help file (NTCMDS.HLP or NTCMDS.INF) resembling that of MS-DOS 6.
PowerShell
Within PowerShell, the help command serves as an alias for the Get-Help Cmdlet, offering a comprehensive, console-driven help system that covers cmdlets, providers, and PowerShell fundamentals.
GNU Bash
In Bash, the builtin help command either lists all built-in commands when used without parameters or provides a summary for a specified command. The syntax is:
help [-dms] [pattern]
OpenVMS
The HELP utility in DCL supplies detailed information on commands and OpenVMS concepts such as time formats and lexical functions, including categorized command listings known as HELP Hints.
Syntax
help [command]
command— identifies the command for which information is requested.
DOSBox
<syntaxhighlight lang="doscon"> Z:\>help To see all supported commands, type help /all. Frequently used commands include: <DIR > View directory contents. <CD > Show or change current directory. <CLS > Clear the screen. <COPY > Duplicate files. ... </syntaxhighlight>
Python
<syntaxhighlight lang="pycon" highlight="3"> >>> help Type help() to enter interactive help, or help(object) to get information about an object. >>> help()
Welcome to Python 2.5! This interactive help tool assists users with modules, keywords, and programming subjects. Enter "quit" to exit. ... </syntaxhighlight>
GNU Octave
<syntaxhighlight lang="text" highlight="1"> octave-3.0.0.exe:1> help
Help is provided for the topics listed below. Additional assistance for built-in functions and operators is available in the online manual. Use the command `doc <topic>' to search the manual index. ... </syntaxhighlight>
See also
Further reading
- Van Wolverton, MS-DOS Commands: Microsoft Quick Reference, 4th Revised edition, Microsoft Press, 1990, ISBN 978-1556152894
- Kathy Ivens; Brian Proffit, OS/2 Inside & Out, Osborne McGraw-Hill, 1993, ISBN 978-0078818714
- Æleen Frisch, Windows 2000 Commands Pocket Reference, O'Reilly Media, 2001, ISBN 978-0-596-00148-3