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@node Help, Mark, M-x, Top
@chapter Help
@kindex Help
@cindex help
@cindex self-documentation
@findex help-command
@kindex C-h
@kindex F1

  XEmacs provides extensive help features accessible through a single
character, @kbd{C-h}.  @kbd{C-h} is a prefix key that is used only for
documentation-printing commands.  The characters that you can type after
@kbd{C-h} are called @dfn{help options}.  One help option is @kbd{C-h};
that is how you ask for help about using @kbd{C-h}.  To cancel, type
@kbd{C-g}.  The function key @key{F1} is equivalent to @kbd{C-h}.

@kindex C-h C-h
@findex help-for-help
  @kbd{C-h C-h} (@code{help-for-help}) displays a list of the possible
help options, and then asks you to type the desired option.  It prompts
with the string:

@smallexample
A B C F I K L M N P S T V W C-c C-d C-f C-i C-k C-n C-w;  ? for more help:
@end smallexample

@noindent
You should type one of those characters.

  Typing a third @kbd{C-h} displays a description of what the options mean;
Emacs still waits for you to type an option.  To cancel, type @kbd{C-g}.

  Most help buffers use a special major mode, Help mode, which lets you
scroll conveniently with @key{SPC} and @key{DEL} or @key{BS}.

@menu
* Help Summary::        Brief list of all Help commands.
* Key Help::            Asking what a key does in XEmacs.
* Name Help::           Asking about a command, variable or function name.
* Apropos::             Asking what pertains to a given topic.
* Library Keywords::    Finding Lisp libraries by keywords (topics).
* Help Mode::           Special features of Help mode and Help buffers.
* Misc Help::           Other help commands.
@end menu

@iftex
@node Help Summary, Help Summary, Help, Help
@end iftex
@ifinfo
@node Help Summary, Key Help, Help, Help
@section Help Summary
@end ifinfo

  Here is a summary of the defined help commands.

@table @kbd
@item C-h a @var{regexp} @key{RET}
Display a list of functions and variables whose names match @var{regexp}
(@code{hyper-apropos}).
@item C-h A @var{regexp}
Show all commands whose names contain matches for @var{regexp}
(@code{command-apropos}).
@item C-h b
Display a table of all key bindings currently in effect, with local
bindings of the current major mode first, followed by all global
bindings (@code{describe-bindings}).
@item C-h c @var{key}
Print the name of the command that @var{key} runs
(@code{describe-key-briefly}).  Here @kbd{c} stands for `character'.  For more
extensive information on @var{key}, use @kbd{C-h k}.
@item C-h d @var{function} @key{RET}
@itemx C-h f @var{function} @key{RET}
Display documentation on the Lisp function named @var{function}
(@code{describe-function}).  Since commands are Lisp functions,
a command name may be used.
@item C-h i
Run Info, the program for browsing documentation files (@code{info}).
The complete XEmacs manual is available online in Info.
@item C-h k @var{key}
Display the name and documentation of the command that @var{key} runs
(@code{describe-key}).
@item C-h l
Display a description of the last 100 characters you typed
(@code{view-lossage}).
@item C-h m
Display documentation of the current major mode (@code{describe-mode}).
@item C-h n
@itemx C-h C-n
Display documentation of XEmacs changes, most recent first
(@code{view-emacs-news}).
@item C-h p
Find packages by topic keyword (@code{finder-by-keyword}).
@item C-h C-p
Display a table of all mouse bindings currently in effect now, with
local bindings of the current major mode first, followed by all global
bindings (@code{describe-pointer}).
@item C-h s
Display current contents of the syntax table, plus an explanation of
what they mean (@code{describe-syntax}).  @xref{Syntax}.
@item C-h t
Enter the XEmacs interactive tutorial (@code{help-with-tutorial}).
@item C-h v @var{var} @key{RET}
Display the documentation of the Lisp variable @var{var}
(@code{describe-variable}).
@item C-h w @var{command} @key{RET}
Print which keys run the command named @var{command} (@code{where-is}).
@item C-h B @key{RET}
Display info on how to deal with Beta versions of XEmacs
(@code{describe-beta}).
@item C-h C @var{group} @key{RET}
Select customization buffer for @var{group} (@code{customize}).
@item C-h F @key{RET}
View the local copy of the XEmacs FAQ (@code{xemacs-local-faq}).
@item C-h C-i @var{file} @key{RET}
Read Info file @var{file} with Info browser (@code{Info-query}).
@item C-h C-c @var{command} @key{RET}
Look up an Emacs command @var{command} in the Emacs manual in the Info
system (@code{Info-goto-emacs-command-node}).
@item C-h C-f @var{function} @key{RET}
Look up an Emacs Lisp function @var{function} in the Elisp manual in the
Info system (@code{Info-elisp-ref}).
@end table

@node Key Help, Name Help, Help Summary, Help
@section Documentation for a Key

@kindex C-h c
@findex describe-key-briefly
  The most basic @kbd{C-h} options are @kbd{C-h c}
(@code{describe-key-briefly}) and @w{@kbd{C-h k}} (@code{describe-key}).
@kbd{C-h c @var{key}} prints in the echo area the name of the command
that @var{key} is bound to.  For example, @kbd{C-h c C-f} prints
@samp{forward-char}.  Since command names are chosen to describe what
the commands do, this is a good way to get a very brief description of
what @var{key} does.

@kindex C-h k
@findex describe-key
  @kbd{C-h k @var{key}} is similar to @kbd{C-h c} but gives more
information.  It displays the documentation string of the function
@var{key} is bound to as well as its name.  @var{key} is a string or
vector of events.  When called interactively, @var{key} may also be a menu
selection.  This information does not usually fit into the echo area, so a
window is used for the display.

  @kbd{C-h c} and @kbd{C-h k} work for any sort of key sequences,
including function keys and mouse events.

@node Name Help, Apropos, Key Help, Help
@section Help by Command or Variable Name

@kindex C-h f
@findex describe-function
@vindex describe-function-show-arglist
  @kbd{C-h f} (@code{describe-function}) reads the name of a Lisp
function using the minibuffer, then displays that function's
documentation string in a window.  Since commands are Lisp functions,
you can use the argument @var{function} to get the documentation of a
command that you know by name.  For example,

@example
C-h f auto-fill-mode @key{RET}
@end example

@noindent
displays the documentation for @code{auto-fill-mode}. Using @kbd{C-h f}
is the only way to see the documentation of a command that is not bound
to any key, that is, a command you would normally call using @kbd{M-x}.
If the variable @code{describe-function-show-arglist} is @code{t},
@code{describe-function} shows its arglist if the @var{function} is not
an autoload function.

  @kbd{C-h f} is also useful for Lisp functions that you are planning to
use in a Lisp program.  For example, if you have just written the
expression @code{(make-vector len)} and want to make sure you are using
@code{make-vector} properly, type @kbd{C-h f make-vector @key{RET}}.
Because @kbd{C-h f} allows all function names, not just command names,
you may find that some of your favorite abbreviations that work in
@kbd{M-x} don't work in @kbd{C-h f}.  An abbreviation may be unique
among command names, yet fail to be unique when other function names are
allowed.

  The function name for @kbd{C-h f} to describe has a default which is
used if you type @key{RET} leaving the minibuffer empty.  The default is
the function called by the innermost Lisp expression in the buffer
around point, @emph{provided} that is a valid, defined Lisp function
name.  For example, if point is located following the text
@samp{(make-vector (car x)}, the innermost list containing point is the
one that starts with @samp{(make-vector}, so the default is to describe the
function @code{make-vector}.

  @kbd{C-h f} is often useful just to verify that you have the right
spelling for the function name.  If @kbd{C-h f} mentions a name from the
buffer as the default, that name must be defined as a Lisp function.  If
that is all you want to know, just type @kbd{C-g} to cancel the @kbd{C-h
f} command, then go on editing.

@kindex C-h w
@findex where-is
  @kbd{C-h w @var{command} @key{RET}} (@code{where-is}) tells you what
keys are bound to @var{command}.  It prints a list of the keys in the
echo area. Alternatively, it informs you that a command is not bound to
any keys, which implies that you must use @kbd{M-x} to call the
command.

@kindex C-h v
@findex describe-variable
  @kbd{C-h v} (@code{describe-variable}) is like @kbd{C-h f} but
describes Lisp variables instead of Lisp functions.  Its default is the
Lisp symbol around or before point, if that is the name of a known Lisp
variable.  @xref{Variables}.

@node Apropos, Library Keywords, Name Help, Help
@section Apropos

@kindex C-h A
@findex command-apropos
@cindex apropos

@table @kbd
@item C-h A
Show only symbols that are names of commands
(@code{command-apropos}).

@item M-x apropos @var{regexp}
Show all symbols whose names contain matches for @var{regexp}.
@end table

  A more sophisticated sort of question to ask is, ``What are the
commands for working with files?''  To ask this question, type @kbd{C-h
a file @key{RET}}, which displays a list of all command names that
contain @samp{file}, including @code{copy-file}, @code{find-file}, and
so on.  With each command name appears a brief description of how to use
the command, and what keys you can currently invoke it with.  For
example, it would say that you can invoke @code{find-file} by typing
@kbd{C-x C-f}.  The @kbd{A} in @kbd{C-h A} stands for `Apropos';
@kbd{C-h A} runs the command @code{command-apropos}.  This command
normally checks only commands (interactive functions); if you specify a
prefix argument, it checks noninteractive functions as well.

  Because @kbd{C-h A} looks only for functions whose names contain the
string you specify, you must use ingenuity in choosing the string.  If
you are looking for commands for killing backwards and @kbd{C-h a
kill-backwards @key{RET}} doesn't reveal any, don't give up.  Try just
@kbd{kill}, or just @kbd{backwards}, or just @kbd{back}.  Be persistent.
Pretend you are playing Adventure.  Also note that you can use a regular
expression as the argument, for more flexibility (@pxref{Regexps}).

  Here is a set of arguments to give to @kbd{C-h a} that covers many
classes of XEmacs commands, since there are strong conventions for
naming the standard XEmacs commands.  By giving you a feel for the
naming conventions, this set should also serve to aid you in developing
a technique for picking @code{apropos} strings.

@quotation
char, line, word, sentence, paragraph, region, page, sexp, list, defun,
rect, buffer, frame, window, face, file, dir, register, mode, beginning,
end, forward, backward, next, previous, up, down, search, goto, kill,
delete, mark, insert, yank, fill, indent, case, change, set, what, list,
find, view, describe, default.
@end quotation

@findex apropos
  To list all Lisp symbols that contain a match for a regexp, not just
the ones that are defined as commands, use the command @kbd{M-x apropos}
instead of @kbd{C-h A}.  This command does not check key bindings by
default; specify a numeric argument if you want it to check them.

@findex apropos-documentation
  The @code{apropos-documentation} command is like @code{apropos} except
that it searches documentation strings for matches for the specified
regular expression.

@findex apropos-value
  The @code{apropos-value} command is like @code{apropos} except that it
searches symbols' values for matches for the specified regular
expression.  This command does not check function definitions or
property lists by default; specify a numeric argument if you want it to
check them.

@vindex apropos-do-all
  If the variable @code{apropos-do-all} is non-@code{nil}, the commands
above all behave as if they had been given a prefix argument.

  If you want more information about a function definition, variable or
symbol property listed in the Apropos buffer, you can click on it with
@kbd{Mouse-2} or move there and type @key{RET}.

@node Library Keywords, Help Mode, Apropos, Help
@section Keyword Search for Lisp Libraries

@kindex C-h p
@findex finder-by-keyword
The @kbd{C-h p} command lets you search the standard Emacs Lisp
libraries by topic keywords.  Here is a partial list of keywords you can
use:

@display
abbrev        abbreviation handling, typing shortcuts, macros
bib           code related to the `bib' bibliography processor
c             C, C++, and Objective-C language support
calendar      calendar and time management support
comm          communications, networking, remote access to files
data          support for editing files of data
docs          support for Emacs documentation
dumped        files preloaded into Emacs
emulations    emulations of other editors
extensions    Emacs Lisp language extensions
faces         support for multiple fonts
frames        support for Emacs frames and window systems
games         games, jokes and amusements
hardware      support for interfacing with exotic hardware
help          support for on-line help systems
hypermedia    support for links between text or other media types
i18n          internationalization and alternate character-set support
internal      code for Emacs internals, build process, defaults
languages     specialized modes for editing programming languages
lisp          Lisp support, including Emacs Lisp
local         code local to your site
maint         maintenance aids for the Emacs development group
mail          modes for electronic-mail handling
matching      various sorts of searching and matching
mouse         mouse support
mule          multi-language extensions
news          support for netnews reading and posting
oop           support for object-oriented programming
outlines      support for hierarchical outlining
processes     process, subshell, compilation, and job control support
terminals     support for terminal types
tex           code related to the TeX formatter
tools         programming tools
unix          front-ends/assistants for, or emulators of, UNIX features
vms           support code for vms
wp            word processing
@end display

@node Help Mode, Misc Help, Library Keywords, Help
@section Help Mode Commands

  Help buffers provide the commands of View mode (@pxref{Misc File
Ops}), plus a few special commands of their own.

@table @kbd
@item @key{SPC}
Scroll forward.
@item @key{DEL}
@itemx @key{BS}
Scroll backward.
@c @item @key{RET}
@c Follow a cross reference at point.
@c @item @key{TAB}
@c Move point forward to the next cross reference.
@c @item S-@key{TAB}
@c Move point back to the previous cross reference.
@c @item Mouse-2
@c Follow a cross reference that you click on.
@end table

  When a command name (@pxref{M-x,, Running Commands by Name}) or
variable name (@pxref{Variables}) appears in the documentation, it
normally appears inside paired single-quotes.

@node Misc Help,  , Help Mode, Help
@section Other Help Commands

@kindex C-h i
@findex info
@cindex Info
@cindex manuals, on-line
@cindex on-line manuals
  @kbd{C-h i} (@code{info}) runs the Info program, which is used for
browsing through structured documentation files.  The entire XEmacs manual
is available within Info.  Eventually all the documentation of the GNU
system will be available.  Type @kbd{h} after entering Info to run
a tutorial on using Info.

  If you specify a numeric argument, @kbd{C-h i} prompts for the name of
a documentation file.  This way, you can browse a file which doesn't
have an entry in the top-level Info menu.  It is also handy when you
need to get to the documentation quickly, and you know the exact name of
the file.

@kindex C-h C-f
@kindex C-h C-k
@findex Info-elisp-ref
@findex Info-goto-emacs-command-node
  There are two special help commands for accessing XEmacs documentation
through Info.  @kbd{C-h C-f @var{function} @key{RET}} enters Info and
goes straight to the documentation of the XEmacs function
@var{function}.  @kbd{C-h C-k @var{key}} enters Info and goes straight
to the documentation of the key @var{key}.  These two keys run the
commands @code{Info-elisp-ref} and
@code{Info-goto-emacs-key-command-node}.

@kindex C-h l
@findex view-lossage
  If something surprising happens, and you are not sure what commands you
typed, use @kbd{C-h l} (@code{view-lossage}).  @kbd{C-h l} prints the last
100 command characters you typed in.  If you see commands that you don't
know, you can use @kbd{C-h c} to find out what they do.

@kindex C-h m
@findex describe-mode
  XEmacs has several major modes.  Each mode redefines a few keys and
makes a few other changes in how editing works.  @kbd{C-h m}
(@code{describe-mode}) prints documentation on the current major mode,
which normally describes all the commands that are changed in this mode.

@kindex C-h b
@findex describe-bindings
  @kbd{C-h b} (@code{describe-bindings}) and @kbd{C-h s}
(@code{describe-syntax}) present information about the current XEmacs
mode that is not covered by @kbd{C-h m}.  @kbd{C-h b} displays a list of
all the key bindings currently in effect, with the local bindings of the
current major mode first, followed by the global bindings (@pxref{Key
Bindings}).  @kbd{C-h s} displays the contents of the syntax table with
explanations of each character's syntax (@pxref{Syntax}).

  You can get a similar list for a particular prefix key by typing
@kbd{C-h} after the prefix key.  (There are a few prefix keys for which
this does not work---those that provide their own bindings for
@kbd{C-h}.  One of these is @key{ESC}, because @kbd{@key{ESC} C-h} is
actually @kbd{C-M-h}, which marks a defun.)

@kindex C-h F
@findex xemacs-local-faq
@kindex C-h n
@findex view-emacs-news
@kindex C-h t
@findex help-with-tutorial
@kindex C-h C-c
@findex describe-copying
@kindex C-h C-d
@findex describe-distribution
@kindex C-h C-w
@findex describe-no-warranty
  The other @kbd{C-h} options display various files of useful
information.  @kbd{C-h C-w} (@code{describe-no-warranty}) displays the
full details on the complete absence of warranty for XEmacs.  @kbd{C-h
n} (@code{view-emacs-news}) displays the file @file{xemacs/etc/NEWS},
which contains documentation on XEmacs changes arranged chronologically.
@kbd{C-h F} (@code{xemacs-local-faq}) displays local version of the
XEmacs frequently-answered-questions-list.  @kbd{C-h t}
(@code{help-with-tutorial}) displays the learn-by-doing XEmacs
tutorial. @kbd{C-h C-c} (@code{describe-copying}) displays the file
@file{xemacs/etc/COPYING}, which tells you the conditions you must obey
in distributing copies of XEmacs.  @kbd{C-h C-d}
(@code{describe-distribution}) displays another file named
@file{xemacs/etc/DISTRIB}, which tells you how you can order a copy of
the latest version of XEmacs.