@c Copyright (C) 1996 John W. Eaton
@c This is part of the Octave manual.
@c For copying conditions, see the file gpl.texi.

@node Help, Programming Utilities, Command History Functions, Top
@chapter Help

@deffn {Command} help
Octave's @code{help} command can be used to print brief usage-style
messages, or to display information directly from an on-line version of
the printed manual, using the GNU Info browser.  If invoked without any
arguments, @code{help} prints a list of all the available operators,
functions, and built-in variables.  If the first argument is @code{-i},
the @code{help} command searches the index of the on-line version of
this manual for the given topics.

For example, the command

@example
help help
@end example

@noindent
prints a short message describing the @code{help} command, and

@example
help -i help
@end example

@noindent
starts the GNU Info browser at this node in the on-line version of the
manual.

@xref{Using Info}, for complete details about how to use the GNU Info
browser to read the on-line version of the manual.
@end deffn

@defvr {Built-in Variable} INFO_FILE
The variable @code{INFO_FILE} names the location of the Octave info file.
The default value is @code{"@value{OCTAVEHOME}/info/octave.info"}.
@end defvr

@defvr {Built-in Variable} INFO_PROGRAM
The variable @code{INFO_PROGRAM} names the info program to run.  Its
initial value is
@code{@value{OCTAVEHOME}/libexec/octave/VERSION/exec/ARCH/info}, but
that value can be overridden by the environment variable
@code{OCTAVE_INFO_PROGRAM}, or the command line argument
@code{--info-program NAME}, or by setting the value of
@code{INFO_PROGRAM} in a startup script.
@end defvr

@defvr {Built-in Variable} suppress_verbose_help_message
If the value of @code{suppress_verbose_help_message} is nonzero, Octave
will not add additional help information to the end of the output from
the @code{help} command and usage messages for built-in commands.
@end defvr