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XEmacs provides extensive help features accessible through a single character, C-h. C-h is a prefix key that is used only for documentation-printing commands. The characters that you can type after C-h are called help options. One help option is C-h; that is how you ask for help about using C-h. To cancel, type C-g. The function key <F1> is equivalent to C-h.
C-h C-h (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:
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: |
You should type one of those characters.
Typing a third C-h displays a description of what the options mean; Emacs still waits for you to type an option. To cancel, type C-g.
Most help buffers use a special major mode, Help mode, which lets you scroll conveniently with <SPC> and <DEL> or <BS>.
• Help Summary | Brief list of all Help commands. | |
8.1 Documentation for a Key | Asking what a key does in XEmacs. | |
8.2 Help by Command or Variable Name | Asking about a command, variable or function name. | |
8.3 Apropos | Asking what pertains to a given topic. | |
8.4 Keyword Search for Lisp Libraries | Finding Lisp libraries by keywords (topics). | |
8.5 Help Mode Commands | Special features of Help mode and Help buffers. | |
8.6 Other Help Commands | Other help commands. |
Here is a summary of the defined help commands.
Display a list of functions and variables whose names match regexp
(hyper-apropos
).
Show all commands whose names contain matches for regexp
(command-apropos
).
Display a table of all key bindings currently in effect, with local
bindings of the current major mode first, followed by all global
bindings (describe-bindings
).
Print the name of the command that key runs
(describe-key-briefly
). Here c stands for ‘character’. For more
extensive information on key, use C-h k.
Display documentation on the Lisp function named function
(describe-function
). Since commands are Lisp functions,
a command name may be used.
Run Info, the program for browsing documentation files (info
).
The complete XEmacs manual is available online in Info.
Display the name and documentation of the command that key runs
(describe-key
).
Display a description of the last 100 characters you typed
(view-lossage
).
Display documentation of the current major mode (describe-mode
).
Display documentation of XEmacs changes, most recent first
(view-emacs-news
).
Find packages by topic keyword (finder-by-keyword
).
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 (describe-pointer
).
Display current contents of the syntax table, plus an explanation of
what they mean (describe-syntax
). See section The Syntax Table.
Enter the XEmacs interactive tutorial (help-with-tutorial
).
Display the documentation of the Lisp variable var
(describe-variable
).
Print which keys run the command named command (where-is
).
Display info on how to deal with Beta versions of XEmacs
(describe-beta
).
Select customization buffer for group (customize
).
View the local copy of the XEmacs FAQ (xemacs-local-faq
).
Read Info file file with Info browser (Info-query
).
Look up an Emacs command command in the Emacs manual in the Info
system (Info-goto-emacs-command-node
).
Look up an Emacs Lisp function function in the Elisp manual in the
Info system (Info-elisp-ref
).
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The most basic C-h options are C-h c
(describe-key-briefly
) and C-h k (describe-key
).
C-h c key prints in the echo area the name of the command
that key is bound to. For example, C-h c C-f prints
‘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 key does.
C-h k key is similar to C-h c but gives more information. It displays the documentation string of the function key is bound to as well as its name. key is a string or vector of events. When called interactively, 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.
C-h c and C-h k work for any sort of key sequences, including function keys and mouse events.
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C-h f (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 function to get the documentation of a
command that you know by name. For example,
C-h f auto-fill-mode <RET> |
displays the documentation for auto-fill-mode
. Using 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 M-x.
If the variable describe-function-show-arglist
is t
,
describe-function
shows its arglist if the function is not
an autoload function.
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 (make-vector len)
and want to make sure you are using
make-vector
properly, type C-h f make-vector <RET>.
Because C-h f allows all function names, not just command names,
you may find that some of your favorite abbreviations that work in
M-x don’t work in 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 C-h f to describe has a default which is
used if you type <RET> leaving the minibuffer empty. The default is
the function called by the innermost Lisp expression in the buffer
around point, provided that is a valid, defined Lisp function
name. For example, if point is located following the text
‘(make-vector (car x)’, the innermost list containing point is the
one that starts with ‘(make-vector’, so the default is to describe the
function make-vector
.
C-h f is often useful just to verify that you have the right spelling for the function name. If 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 C-g to cancel the C-h f command, then go on editing.
C-h w command <RET> (where-is
) tells you what
keys are bound to 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 M-x to call the
command.
C-h v (describe-variable
) is like 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. See section Variables.
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Show only symbols that are names of commands
(command-apropos
).
Show all symbols whose names contain matches for regexp.
A more sophisticated sort of question to ask is, “What are the
commands for working with files?” To ask this question, type C-h
a file <RET>, which displays a list of all command names that
contain ‘file’, including copy-file
, 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 find-file
by typing
C-x C-f. The A in C-h A stands for ‘Apropos’;
C-h A runs the command command-apropos
. This command
normally checks only commands (interactive functions); if you specify a
prefix argument, it checks noninteractive functions as well.
Because 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 C-h a kill-backwards <RET> doesn’t reveal any, don’t give up. Try just kill, or just backwards, or just back. Be persistent. Pretend you are playing Adventure. Also note that you can use a regular expression as the argument, for more flexibility (see section Syntax of Regular Expressions).
Here is a set of arguments to give to 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 apropos
strings.
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.
To list all Lisp symbols that contain a match for a regexp, not just the ones that are defined as commands, use the command M-x apropos instead of C-h A. This command does not check key bindings by default; specify a numeric argument if you want it to check them.
The apropos-documentation
command is like apropos
except
that it searches documentation strings for matches for the specified
regular expression.
The apropos-value
command is like 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.
If the variable apropos-do-all
is non-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 Mouse-2 or move there and type <RET>.
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The 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:
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 |
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Help buffers provide the commands of View mode (see section Miscellaneous File Operations), plus a few special commands of their own.
Scroll forward.
Scroll backward.
When a command name (see section Running Commands by Name) or variable name (see section Variables) appears in the documentation, it normally appears inside paired single-quotes.
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C-h i (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 h after entering Info to run
a tutorial on using Info.
If you specify a numeric argument, 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.
There are two special help commands for accessing XEmacs documentation
through Info. C-h C-f function <RET> enters Info and
goes straight to the documentation of the XEmacs function
function. C-h C-k key enters Info and goes straight
to the documentation of the key key. These two keys run the
commands Info-elisp-ref
and
Info-goto-emacs-key-command-node
. (GNU Emacs binds C-h C-f
to Info-goto-emacs-command-node
, but this is less helpful to
programmers.)
If something surprising happens, and you are not sure what commands you
typed, use C-h l (view-lossage
). C-h l prints the last
100 command characters you typed in. If you see commands that you don’t
know, you can use C-h c to find out what they do.
XEmacs has several major modes. Each mode redefines a few keys and
makes a few other changes in how editing works. C-h m
(describe-mode
) prints documentation on the current major mode,
which normally describes all the commands that are changed in this mode.
C-h b (describe-bindings
) and C-h s
(describe-syntax
) present information about the current XEmacs
mode that is not covered by C-h m. 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 (see section Customizing Key Bindings). C-h s displays the contents of the syntax table with
explanations of each character’s syntax (see section The Syntax Table).
You can get a similar list for a particular prefix key by typing 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 C-h. One of these is <ESC>, because <ESC> C-h is actually C-M-h, which marks a defun.)
The other C-h options display various files of useful
information. C-h C-w (describe-no-warranty
) displays the
full details on the complete absence of warranty for XEmacs. C-h
n (view-emacs-news
) displays the file ‘xemacs/etc/NEWS’,
which contains documentation on XEmacs changes arranged
chronologically. C-h F (xemacs-local-faq
) displays the
local version of the XEmacs FAQ (Frequently Answered Questions list).
C-h t (help-with-tutorial
) displays the learn-by-doing
XEmacs tutorial. C-h C-c (describe-copying
) displays the
file ‘xemacs/etc/COPYING’, which tells you the conditions you
must obey in distributing copies of XEmacs. C-h C-d
(describe-distribution
displays the section of the FAQ that
tells you how you can get the latest version of XEmacs.
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