help (command)

The end of the HELP command output from RT-11SJ displayed on a VT100.
The BusyBox HELP command

In computing, help is a command in various command line shells such as COMMAND.COM, cmd.exe, Bash, 4DOS/4NT, Windows PowerShell, Singularity shell, Python and GNU Octave. It provides online information about available commands and the shell environment.[1]

The command is available in operating systems such as DOS, OS/2, Microsoft Windows, ReactOS, OpenVOS[2], KolibriOS[3] and also in the DEC RT-11[4] and TOPS-20[5] operating systems. Furthermore it is available in the open source MS-DOS emulator DOSBox and in the EFI shell.[6] The DEC OS/8 CCL help command prints information on specified OS/8 programs.[7] On Unix, the command is part of the Source Code Control System and prints help information for the SCCS commands.

Syntax

help [command]

Arguments:

  • command This command-line argument specifies the name of the command about which information is to be displayed.

Implementations

DOS

The help command is available in MS-DOS 5.x and later versions of the software. If no arguments are provided, the command lists the contents of DOSHELP.HLP. In MS-DOS 6.x this command exists as FASTHELP. In DR-DOS, HELP is a batch file that launches DR-DOS' internal help program, DOSBOOK.

  • 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.
  • 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.

4DOS/4NT

The 4DOS/4NT help command uses a text user interface to display the online help.

cmd.exe

Used 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.

Windows PowerShell

In Windows 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.

GNU Bash

In Bash, the builtin command help[8] lists all Bash builtin commands if used without arguments. Otherwise, it prints a brief summary of a command. Its syntax is:

help [-dms] [pattern]

Examples

DOSBox

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.
...

Python

>>> help
Type 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 out
the tutorial on the Internet at https://www.python.org/doc/tut/.

Enter the name of any module, keyword, or topic to get help on writing
Python programs and using Python modules.  To quit this help utility and
return to the interpreter, just type "quit".
...

GNU Octave

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.
...

See also

References

  1. ↑ Microsoft TechNet Help article
  2. ↑ http://stratadoc.stratus.com/vos/19.1.0/r098-19/wwhelp/wwhimpl/common/html/r098-19.pdf
  3. ↑ http://wiki.kolibrios.org/wiki/Shell
  4. ↑ http://paleoferrosaurus.com/beta/documents/rt11help.html#HELP
  5. ↑ "TOPS-20 Command manual" (PDF).
  6. ↑ "EFI Shells and Scripting". Intel. Retrieved 2013-09-25.
  7. ↑ "Concise Command Language" (CCL)."OS/8 Handbook" (PDF). April 1974. Retrieved 28 November 2017.
  8. ↑ "Bash Reference Manual". www.gnu.org. Retrieved 2016-05-09.
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