help (command)

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

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. The command is also available in the DEC RT-11 operating system. 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. 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^[1] 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

DOS

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.
...

References

Microsoft TechNet Help article

↑ "Bash Reference Manual". www.gnu.org. Retrieved 2016-05-09.

Windows command-line programs and shell builtins

COMMAND.COM Command Prompt Windows PowerShell Recovery Console

File system navigation	cd (chdir) dir popd pushd tree

File management	attrib cacls cipher compact copy del (erase) deltree expand icacls makecab md (mkdir) move rd (rmdir) recover ren (rename) replace rmdir robocopy xcopy

Disk management	chkdsk convert defrag diskcomp diskcopy diskpart fdisk format label subst scandisk sys vol vssadmin

Processes	exit kill powercfg runas sc shutdown start taskkill tasklist

Registry	assoc ftype reg regini regsvr32

User environment	date mode path set setx time title ver whoami

File contents	comp edit edlin fc find findstr print type

Scripting	choice clip cscript doskey echo for goto if more pause prompt rem

Networking	arp getmac hostname ipconfig net use netsh netstat nslookup PathPing ping route tracert

Maintenance and care	driverquery msiexec ntbackup sfc systeminfo w32tm WBAdmin winsat wmic

Boot management	bcdedit bootcfg fixboot fixmbr

Software development	debug exe2bin QBasic

Miscellaneous	cls help

List of DOS commands Environment variables

Unix command-line interface programs and shell builtins

File system	cat chmod chown chgrp cksum cmp cp dd du df file fsck fuser ln ls mkdir mount mv pax pwd rm rmdir split tee touch type umask

Processes	at bg chroot cron fg kill killall nice pgrep pkill ps pstree time top

User environment	clear env exit finger history logname mesg passwd su sudo uptime talk tput uname w wall who whoami write

Text processing	awk banner basename comm csplit cut diff dirname ed ex fmt fold head iconv join less more nl paste printf sed sort spell strings tail tr uniq vi wc xargs yes

Shell builtins	alias cd echo test unset wait

Networking	dig host ifconfig inetd netcat netstat nslookup ping rdate rlogin route ssh traceroute

Searching	find grep locate whatis whereis

Documentation	apropos help man

Miscellaneous	bc dc cal expr lp od sleep true and false

List of Unix commands

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