In 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 and GNU Octave. It provides online information about available commands and the shell environment. Implementations The command is available in operating systems such as Multics, Heath Company HDOS, DOS, IBM OS/2, eComStation, ArcaOS, IBM i, Microsoft Windows, ReactOS, THEOS/OASIS, Zilog Z80-RIO, Microware OS-9, Stratus OpenVOS, HP MPE/iX, Motorola VERSAdos, KolibriOS and also in the DEC RT-11, RSX-11, TOPS-10 and TOPS-20 operating systems. Furthermore it is available in the open source MS-DOS emulator DOSBox and in the EFI shell. On Unix, the command is part of the Source Code Control System and prints help information for the SCCS commands. Multics 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. DEC OS/8 The DEC OS/8 CCL help command prints information on specified OS/8 programs. DOS MS-DOS The help command is available in MS-DOS 5.x and later versions of the software. 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. PC DOS 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. PC-MOS The Software Link's PC-MOS includes an implementation of help. Like the rest of the operating system, it is licensed under the GPL v3. DR-DOS In DR-DOS, help is a batch file that launches DR-DOS' internal help program, dosbook. ROM-DOS Datalight ROM-DOS includes an implementation of the command. ROM-DOS was introduced in 1989 as an MS-DOS compatible operating system designed for embedded systems. FreeDOS The FreeDOS version was developed by Joe Cosentino. 4DOS/4NT The 4DOS/4NT help command uses a text user interface to