Go to the previous, next section.
This chapter contains several brief topics that do not fit anywhere else.
GNUS is an Emacs subsystem for reading and responding to netnews. You can use GNUS to browse through news groups, look at summaries of articles in specific group, and read articles of interest. You can respond to authors or write replies to all the readers of a news group.
This section introduces GNUS and describes several basic
features. Full documentation will appear elsewhere.
To start GNUS, type M-x gnus RET.
GNUS creates and uses three Emacs buffers, each with its own particular purpose and its own major mode.
The Newsgroup buffer contains a list of newsgroups. This is the first buffer that GNUS displays when it starts up. Normally the list contains only the newsgroups to which you subscribe (which are listed in your `.newsrc' file) and which contain unread articles. Use this buffer to select a specific newsgroup.
The Summary buffer lists the articles in a single newsgroup, including their subjects, their numbers, and who posted them. GNUS creates a Summary buffer for a newsgroup when you select the group in the Newsgroup buffer. Use this buffer to select an article, and to move around in an article.
The Article buffer displays the text of an article. You rarely need to select this buffer because you can read the text while keeping the Summary buffer selected.
At startup, GNUS reads your `.newsrc' news initialization file and attempts to communicate with the local news server, which is a repository of news articles. The news server need not be the same computer you are logged in on.
If you start GNUS and connect to the server, but do not see any newsgroups listed in the Newsgroup buffer, type L to get a listing of all the newsgroups. Then type u to unsubscribe from particular newsgroups. (Move the cursor using n and p or the usual Emacs commands.)
When you quit GNUS with q, it automatically records in your `.newsrc' initialization file the subscribed or unsubscribed status of all newsgroups, except for groups you have "killed". (You do not need to edit this file yourself, but you may.) When new newsgroups come into existence, GNUS adds them automatically.
Reading news is a two step process:
Each buffer has commands particular to it, but commands that do the same things have similar keybindings. Here are commands for the Newsgroup and Summary buffers:
In the Summary buffer, exit the current newsgroup and return to the
Newsgroup buffer. Thus, typing q twice quits GNUS.
When you quit GNUS by typing q, GNUS writes information
in the file `.newsrc' describing all newsgroups except those you
have "killed."
In the Summary buffer,
Thus, you can move through all the articles by repeatedly typing SPC.
In the Summary buffer, scroll the text of the article backwards.
Emacs provides several commands for sorting text in the buffer. All operate on the contents of the region (the text between point and the mark). They divide the text of the region into many sort records, identify a sort key for each record, and then reorder the records into the order determined by the sort keys. The records are ordered so that their keys are in alphabetical order, or, for numeric sorting, in numeric order. In alphabetic sorting, all upper case letters `A' through `Z' come before lower case `a', in accord with the ASCII character sequence.
The various sort commands differ in how they divide the text into sort
records and in which part of each record is used as the sort key. Most of
the commands make each line a separate sort record, but some commands use
paragraphs or pages as sort records. Most of the sort commands use each
entire sort record as its own sort key, but some use only a portion of the
record as the sort key.
Specify which field to sort by with a numeric argument: 1 to sort by field 1, etc. A negative argument means count fields from the right instead of from the left; thus, minus 1 means sort by the last field. If several lines have identical contents in the field being sorted, they keep same relative order that they had in the original buffer.
For example, if the buffer contains this:
On systems where clash detection (locking of files being edited) is implemented, Emacs also checks the first time you modify a buffer whether the file has changed on disk since it was last visited or saved. If it has, you are asked to confirm that you want to change the buffer.
then applying M-x sort-lines to the entire buffer produces this:
On systems where clash detection (locking of files being edited) is implemented, Emacs also checks the first time you modify a buffer saved. If it has, you are asked to confirm that you want to change the buffer. whether the file has changed on disk since it was last visited or
where the upper case `O' sorts before all lower case letters. If you use C-u 2 M-x sort-fields instead, you get this:
implemented, Emacs also checks the first time you modify a buffer saved. If it has, you are asked to confirm that you want to change the buffer. On systems where clash detection (locking of files being edited) is whether the file has changed on disk since it was last visited or
where the sort keys were `Emacs', `If', `buffer',
`systems' and `the'.
M-x sort-columns requires more explanation. You specify the columns by putting point at one of the columns and the mark at the other column. Because this means you cannot put point or the mark at the beginning of the first line to sort, this command uses an unusual definition of `region': all of the line point is in is considered part of the region, and so is all of the line the mark is in.
For example, to sort a table by information found in columns 10 to 15,
you could put the mark on column 10 in the first line of the table, and
point on column 15 in the last line of the table, and then run
sort-columns. Equivalently, you could run it with the mark on
column 15 in the first line and point on column 10 in the last line.
This can be thought of as sorting the rectangle specified by point and
the mark, except that the text on each line to the left or right of the
rectangle moves along with the text inside the rectangle.
See section Rectangles.
Many of the sort commands ignore case differences when comparing, if
sort-fold-case is non-nil.
Emacs has commands for passing single command lines to inferior shell processes; it can also run a shell interactively with input and output to an Emacs buffer `*shell*'.
shell-command).
shell-command-on-region).
M-! (shell-command) reads a line of text using the
minibuffer executes it as a shell command in a subshell made just for
this command. Standard input for the command comes from the null
device. If the shell command produces any output, the output goes into
an Emacs buffer named `*Shell Command Output*', which is displayed
in another window but not selected. A numeric argument, as in M-1
M-!, directs this command to insert any output into the current
buffer. In that case, point is left before the output and the mark is
set after the output.
If the shell command line ends in `&', it runs asynchronously.
M-| (shell-command-on-region) is like M-! but passes
the contents of the region as input to the shell command, instead of no
input. If a numeric argument is used, meaning insert output in the current
buffer, then the old region is deleted first and the output replaces it as
the contents of the region.
Both M-! and M-| use shell-file-name to specify the
shell to use. This variable is initialized based on your SHELL
environment variable when Emacs is started. If the file name does not
specify a directory, the directories in the list exec-path are
searched; this list is initialized based on the environment variable
PATH when Emacs is started. Your `.emacs' file can override
either or both of these default initializations.
With M-! and M-|, Emacs has to wait until the shell command completes. To stop waiting, type C-g to quit; that also kills the shell command.
To run a subshell interactively, putting its typescript in an Emacs buffer, use M-x shell. This creates (or reuses) a buffer named `*shell*' and runs a subshell with input coming from and output going to that buffer. That is to say, any "terminal output" from the subshell goes into the buffer, advancing point, and any "terminal input" for the subshell comes from text in the buffer. To give input to the subshell, go to the end of the buffer and type the input, terminated by RET.
Emacs does not wait for the subshell to do anything. You can switch windows or buffers and edit them while the shell is waiting, or while it is running a command. Output from the subshell waits until Emacs has time to process it; this happens whenever Emacs is waiting for keyboard input or for time to elapse.
To make multiple subshells, rename the buffer `*shell*' to
something different using M-x rename-uniquely. Then type M-x
shell again to create a new buffer `*shell*' with its own
subshell. If you rename this buffer as well, you can create a third
one, and so on. All the subshells run independently and in parallel.
The file name used to load the subshell is the value of the variable
explicit-shell-file-name, if that is non-nil. Otherwise, the
environment variable ESHELL is used, or the environment variable
SHELL if there is no ESHELL. If the file name specified
is relative, the directories in the list exec-path are searched
(see section Single Shell Commands).
As soon as the subshell is started, it is sent as input the contents of
the file `~/.emacs_shellname', if that file exists, where
shellname is the name of the file that the shell was loaded from.
For example, if you use bash, the file sent to it is
`~/.emacs_bash'.
cd, pushd and popd commands given to the inferior
shell are watched by Emacs so it can keep the `*shell*' buffer's
default directory the same as the shell's working directory. These
commands are recognized syntactically by examining lines of input that are
sent. If you use aliases for these commands, you can tell Emacs to
recognize them also. For example, if the value of the variable
shell-pushd-regexp matches the beginning of a shell command line,
that line is regarded as a pushd command. Change this variable when
you add aliases for `pushd'. Likewise, shell-popd-regexp and
shell-cd-regexp are used to recognize commands with the meaning of
`popd' and `cd'. These commands are recognized only at the
beginning of a shell command line.
If Emacs gets an error while trying to handle what it believes is a
`cd', `pushd' or `popd' command, it runs the hook
shell-set-directory-error-hook (see section Hooks).
If Emacs does not properly track changes in the current directory of the subshell, use the command M-x dirs to ask the shell what its current directory is. This command works for shells that support the most common command syntax; it may not work for unusual shells.
The shell buffer uses Shell mode, which defines several special keys
attached to the C-c prefix. They are chosen to resemble the usual
editing and job control characters present in shells that are not under
Emacs, except that you must type C-c first. Here is a complete list
of the special key bindings of Shell mode:
comint-send-input). When a line is
copied, any text at the beginning of the line that matches the variable
shell-prompt-pattern is left out; this variable's value should be
a regexp string that matches the prompts that your shell uses.
comint-dynamic-complete). TAB also completes history
references (see section Shell History References) and environment variable names.
The variable shell-completion-fignore specifies a list of file
name extensions to ignore in Shell mode completion. The default setting
ignores file names ending in `~', `#' or `%'. Other
related Comint modes use the variable comint-completion-fignore
instead.
comint-dynamic-list-filename-completions).
comint-bol).
comint-delchar-or-maybe-eof). Typed at the end of the shell
buffer, C-d sends EOF to the subshell. Typed at any other
position in the buffer, C-d deletes a character as usual.
comint-kill-input).
backward-kill-word).
comint-interrupt-subjob).
comint-stop-subjob).
comint-quit-subjob).
comint-kill-output). This is useful if a shell command spews
out lots of output that just gets in the way.
comint-show-output).
comint-show-maximum-output).
shell-forward-command). The variable shell-command-regexp
specifies how to recognize the end of a command.
shell-backward-command).
Alternatively, you can arrange for Emacs to notice password prompts and turn off echoing for them, as follows:
(add-hook `comint-output-filter-functions
`comint-watch-for-password-prompt)
Shell mode also customizes the paragraph commands so that only shell
promps start new paragraphs. Thus, a paragraph consists of an input
command plus the output that follows it in the buffer.
Shell mode is a derivative of Comint mode, a general purpose mode for communicating with interactive subprocesses. Most of the features of Shell mode actually come from Comint mode, as you can see from the command names listed above. The specialization of Shell mode in particular include the choice of regular expression for detecting prompts, the directory tracking feature, and a few user commands.
Other Emacs features that use variants of Comint mode include GUD
(see section Running Debuggers Under Emacs) and M-x run-lisp (see section Running an External Lisp).
You can use M-x comint-run to execute any program of your choice in a subprocess using unmodified Comint mode--without the specializations of Shell mode.
Shell buffers support three ways of repeating earlier commands. You can use the same keys used in the minibuffer; these work much as they do in the minibuffer, inserting text from prior commands while point remains always at the end of the buffer. You can move through the buffer to previous inputs in their original place, then resubmit them or copy them to the end. Or you can use a `!'-style history reference.
Shell buffers provide a history of previously entered shell commands. To reuse shell commands from the history, use the editing commands M-p, M-n, M-r and M-s. These work just like the minibuffer history commands except that they operate on the text at the end of the shell buffer, where you would normally insert text to send to the shell.
M-p fetches an earlier shell command to the end of the shell buffer. Successive use of M-p fetches successively earlier shell commands, each replacing any text that was already present as potential shell input. M-n does likewise except that it finds successively more recent shell commands from the buffer.
The history search commands M-r and M-s read a regular expression and search through the history for a matching command. Aside from the choice of which command to fetch, they work just like M-p and M-r. If you enter an empty regexp, these commands reuse the same regexp used last time.
When you find the previous input you want, you can resubmit it by typing RET, or you can edit it first and then resubmit it if you wish.
These commands get the text of previous shell commands from a special history list, not from the shell buffer itself. Thus, editing the shell buffer, or even killing large parts of it, does not affect the history that these commands access.
comint-previous-prompt).
comint-next-prompt).
comint-copy-old-input). This is useful if you
move point back to a previous command. After you copy the command, you
can submit the copy as input with RET. If you wish, you can
edit the copy before resubmitting it.
Moving to a previous input and then copying it with C-c RET produces the same results--the same buffer contents--that you would get by using M-p enough times to fetch that previous input from the history list. However, C-c RET copies the text from the buffer, which can be different from what is in the history list (if you edit the input in the buffer after it has been sent).
Various shells including csh and bash support history references
that begin with `!' and `^'. Shell mode now understands this
syntax. If you insert a history reference and type TAB, this
searches the input history for a matching command, performs substitution
if necessary, and places the result in the buffer in place of the
history reference. For example, you can fetch the most recent
command beginning with `mv' with ! m v TAB. You could
then resubmit this command to the shell by typing RET as usual.
History references take effect only following a shell prompt. The
variable comint-prompt-regexp specifies how to recognize a shell
prompt.
If the variable comint-scroll-to-bottom-on-input is
non-nil, insertion and yank commands scroll the selected window
the bottom before inserting.
If comint-scroll-show-maximum-output is non-nil (which is the
default), then scrolling due to arrival of output tries to place the
last line of text at the bottom line of the window, so as to show as
much useful text as possible. (This mimics the scrolling behavior of
many terminals.)
By setting comint-scroll-to-bottom-on-output, you can opt for
having point jump to the end of the buffer whenever output arrives--no
matter where in the buffer point was before. If the value is
this, point jumps in the selected window. If the value is
all, point jumps in each window that shows the comint buffer. If
the value is other, point jumps in all nonselected windows that
show the current buffer. The default value is nil, which means
point does not jump to the end.
The variable comint-input-ignoredups controls whether successive
identical inputs are stored in the input history. A non-nil
value means to omit an input that is the same as the previous input.
The default is nil, which means to store each input even if it is
equal to the previous input.
Three variables customize file name completion. The variable
comint-completion-addsuffix controls whether completion inserts a
space or a slash to indicate a fully completed file or directory name
(non-nil means do insert a space or slash).
comint-completion-recexact, if non-nil, directs TAB
to choose the shortest possible completion if the usual Emacs completion
algorithm cannot add even a single character.
comint-completion-autolist, if non-nil, says to list all
the possible completions whenever completion is not exact.
Shell mode can optionally expand history references in the buffer when
you send them to the shell. To request this, set the variable
comint-input-autoexpand to input.
You can make SPC perform history expansion by binding SPC to
the command comint-magic-space.
The command comint-dynamic-complete-variable does variable name
completion using the environment variables as set within Emacs. The
variables controlling filename completion apply to variable name
completion too. This command is normally available through the menu
bar.
Command completion normally considers only executable files.
If you set shell-command-execonly to nil,
it considers nonexecutable files as well.
In a new Shell mode buffer, the input history is initialized from the
file name specified in the variable shell-input-ring-file-name.
By default, this is "~/.history".
You can now configure the behavior of `pushd'. Variables control
whether `pushd' behaves like `cd' if no argument is given
(shell-pushd-tohome), pop rather than rotate with a numeric
argument (shell-pushd-dextract), and only add directories to the
directory stack if they are not already on it
(shell-pushd-dunique). The values you choose should match the
underlying shell, of course.
Emacs provides two commands for logging in to another computer and communicating with it through an Emacs buffer.
Use M-x telnet to set up a Telnet connection to another
computer. (Telnet is the standard Internet protocol for remote login.)
It reads the host name of the other computer as an argument with the
minibuffer. Once the connection is established, talking to the other
computer works like talking to a subshell: you can edit input with the
usual Emacs commands, and send it a line at a time by typing RET.
The output is inserted in the Telnet buffer interspersed with the input.
Use M-x rlogin to set up an Rlogin connection. Rlogin is
another remote login communication protocol, essentially much like the
Telnet protocol but incompatible with it, and supported only by
Unix-like systems. Rlogin's advantages are that you can arrange not to
have to give your user name and password when communicating between two
machines you frequently use, and that you can make an 8-bit-clean
connection. (To do that in Emacs, set rlogin-explicit-args to
("-8").)
M-x rlogin sets up the default file directory of the Emacs buffer to access the remote host via FTP (see section File Names), and it tracks the shell commands that change the current directory just like Shell mode.
Narrowing means focusing in on some portion of the buffer, making the rest temporarily inaccessible. The portion which you can still get to is called the accessible portion. Cancelling the narrowing, and making the entire buffer once again accessible, is called widening. The amount of narrowing in effect in a buffer at any time is called the buffer's restriction.
narrow-to-region).
widen).
narrow-to-page).
When you have narrowed down to a part of the buffer, that part appears to
be all there is. You can't see the rest, you can't move into it (motion
commands won't go outside the accessible part), you can't change it in any
way. However, it is not gone, and if you save the file all the inaccessible
text will be saved. In addition to sometimes making it easier to
concentrate on a single subroutine or paragraph by eliminating clutter,
narrowing can be used to restrict the range of operation of a replace
command or repeating keyboard macro. The word `Narrow' appears in the
mode line whenever narrowing is in effect.
The primary narrowing command is C-x n n (narrow-to-region).
It sets the current buffer's restrictions so that the text in the current
region remains accessible but all text before the region or after the region
is invisible. Point and mark do not change.
Alternatively, use C-x n p (narrow-to-page) to narrow
down to the current page. See section Pages, for the definition of a page.
The way to undo narrowing is to widen with C-x n w (widen).
This makes all text in the buffer accessible again.
You can get information on what part of the buffer you are narrowed down to using the C-x = command. See section Cursor Position Information.
Because narrowing can easily confuse users who do not understand it,
narrow-to-region is normally a disabled command. Attempting to use
this command asks for confirmation and gives you the option of enabling it;
once you enable the command, confirmation will no longer be required for
it. See section Disabling Commands.
The Emacs commands for making hardcopy let you print either an entire buffer or just part of one, either with or without page headers. See also the hardcopy commands of Dired (see section Miscellaneous File Operations) and the diary (see section Commands Displaying Diary Entries).
print-buffer but prints only the current region.
lpr-buffer but prints only the current region.
All the hardcopy commands pass extra switches to the lpr
program based on the value of the variable lpr-switches. Its
value should be a list of strings, each string an option starting with
`-'. For example, to use a printer named `nearme', set
lpr-switches like this:
(setq lpr-switches '("-Pnearme"))
Two-column mode lets you conveniently edit two side-by-side columns of text. It uses two side-by-side windows, each showing its own buffer.
There are three ways to enter two-column mode:
tc-two-columns). If the right-hand buffer doesn't already
exist, it starts out empty; the current buffer's contents are not
changed.
This command is appropriate when the current buffer contains just one column and you want to add another column.
tc-split). The current
buffer becomes the left-hand buffer, but the text in the right-hand
column is moved into the right-hand buffer. The current column
specifies the split point. Splitting starts with the current line and
continues to the end of the buffer.
This command is appropriate when you have a buffer that already contains two-column text, and you wish to separate the columns temporarily.
tc-associate-buffer).
C-x 6 s looks for a column separator which is a string that appears on each line between the two columns. You can specify the width of the separator with a numeric argument to C-x 6 s; that many characters, before point, constitute the separator string. By default, the width is 1, so the column separator is the character before point.
When a line has the separator at the proper place, C-x 6 s puts the text after the separator into the right-hand buffer, and deletes the separator. Lines that don't have the column separator at the proper place remain unsplit; they stay in the left-hand buffer, and the right-hand buffer gets an empty line to correspond. (This is the way to write a line which "spans both columns while in two-column mode: write it in the left-hand buffer, and put an empty line in the right-hand buffer.)
It's not a good idea to use ordinary scrolling commands during two-column editing, because that separates the two parts of each split line. Instead, use these special scroll commands:
tc-scroll-up).
tc-scroll-down).
tc-recenter).
When you have edited both buffers as you wish, merge them with
C-x 6 1 (tc-merge). This copies the text from the
right-hand buffer as a second column in the other buffer. To go back to
two-column editing, use C-x 6 s.
Use C-x 6 d to disassociate the two buffers, leaving each as it
stands (tc-dissociate). If the other buffer, the one not current
when you type C-x 6 d, is empty, C-x 6 d kills it.
There is a special major mode for editing binary files: Hexl mode. To use it, use M-x hexl-find-file instead of C-x C-f to visit the file. This command converts the file's contents to hexadecimal and lets you edit the translation. When you save the file, it is converted automatically back to binary.
You can also use M-x hexl-mode to translate an existing buffer into hex. This is useful if you visit a file normally and then discover it is a binary file.
Ordinary text characters overwrite in Hexl mode. This is to reduce the risk of accidentally spoiling the alignment of data in the file. There are special commands for insertion. Here is a list of the commands of Hexl mode:
hexl-mode.
Various programs such as mail can invoke your choice of editor
to edit a particular piece of text, such as a message that you are
sending. By convention, these programs use the environment variable
EDITOR to specify which editor to run. If you set EDITOR
to `emacs', they invoke Emacs--but in an inconvenient fashion, by
starting a new, separate Emacs process. This is inconvenient because it
takes time and because the new Emacs process doesn't share the buffers
in the existing Emacs process.
You can arrange to use your existing Emacs process as the editor for
programs like mail by using the Emacs client and Emacs server
programs. Here is how.
First, the preparation. Within Emacs, call the function
server-start. (Your `.emacs' file can do this automatically
if you add the expression (server-start) to it.) Then, outside
Emacs, set the EDITOR environment variable to
`emacsclient'.
Then, whenever any program invokes your specified EDITOR
program, the effect is to send a message to your principal Emacs telling
it to visit a file. (That's what the program emacsclient does.)
Emacs obeys silently; it does not immediately switch to the new file's
buffer. When you want to do that, type C-x #
(server-edit).
When you've finished editing that buffer, type C-x # again.
This saves the file and sends a message back to the emacsclient
program telling it to exit. The programs that use EDITOR wait
for the "editor" (actually, emacsclient) to exit. C-x #
also checks to see if any other files are pending for you to edit, and
selects the next one.
You can switch to a server buffer manually if you wish; you don't have
to arrive at it with C-x #. But C-x # is the only way to
say that you are "finished" with one.
If you set the variable server-window to a window or a frame,
C-x # displays the server buffer in that window or in that frame.
While mail or another application is waiting for
emacsclient to finish, emacsclient does not read terminal
input. So the terminal that mail was using is effectively
blocked for the duration. In order to edit with your principal Emacs,
you need to be able to use it without using that terminal. There are
two ways to do this:
mail and the principal Emacs in two
separate windows. While mail is waiting for emacsclient,
the window where it was running is blocked, but you can use Emacs by
switching windows.
mail;
then, emacsclient blocks only the subshell under Emacs; you can
still use Emacs to edit the file.
Some programs write temporary files for you to edit. After you edit
the temporary file, the program reads it back and deletes it. If the
Emacs server is later asked to edit the same file name, it should assume
this has nothing to do with the previous occasion for that file name.
The server accomplishes this by killing the temporary file's buffer when
you finish with the file. Use the variable
server-temp-file-regexp to specify which files are temporary in
this sense; its value should be a regular expression that matches file
names that are temporary.
You can use the Desktop library to save the state of Emacs from one session to another. Saving the state means that Emacs starts up with the same set of buffers, major modes, buffer positions, and so on that the previous Emacs session had.
To use Desktop, you should first add these lines to your `.emacs' file, preferably at or near the end:
(load "desktop") (desktop-load-default) (desktop-read)
Then, to enable state saving in a particular Emacs session, use the
command M-x desktop-save. Once you have done this, the state of
this Emacs session will be saved when you exit Emacs.
In order for Emacs to recover the state from a previous session, you must start it with the same current directory as you used when you started the previous session.
A recursive edit is a situation in which you are using Emacs
commands to perform arbitrary editing while in the middle of another
Emacs command. For example, when you type C-r inside of a
query-replace, you enter a recursive edit in which you can change
the current buffer. On exiting from the recursive edit, you go back to
the query-replace.
Exiting the recursive edit means returning to the unfinished
command, which continues execution. To exit, type C-M-c
(exit-recursive-edit).
You can also abort the recursive edit. This is like exiting, but
also quits the unfinished command immediately. Use the command C-]
(abort-recursive-edit) for this. See section Quitting and Aborting.
The mode line shows you when you are in a recursive edit by displaying square brackets around the parentheses that always surround the major and minor mode names. Every window's mode line shows this, in the same way, since being in a recursive edit is true of Emacs as a whole rather than any particular window or buffer.
It is possible to be in recursive edits within recursive edits. For
example, after typing C-r in a query-replace, you may type a
command that enters the debugger. This begins a recursive editing level
for the debugger, within the recursive editing level for C-r.
Mode lines display a pair of square brackets for each recursive editing
level currently in progress.
Exiting the inner recursive edit (such as, with the debugger c command) resumes the command running in the next level up. When that command finishes, you can then use C-M-c to exit another recursive editing level, and so on. Exiting applies to the innermost level only. Aborting also gets out of only one level of recursive edit; it returns immediately to the command level of the previous recursive edit. If you wish, you can then abort the next recursive editing level.
Alternatively, the command M-x top-level aborts all levels of recursive edits, returning immediately to the top level command reader.
The text being edited inside the recursive edit need not be the same text that you were editing at top level. It depends on what the recursive edit is for. If the command that invokes the recursive edit selects a different buffer first, that is the buffer you will edit recursively. In any case, you can switch buffers within the recursive edit in the normal manner (as long as the buffer-switching keys have not been rebound). You could probably do all the rest of your editing inside the recursive edit, visiting files and all. But this could have surprising effects (such as stack overflow) from time to time. So remember to exit or abort the recursive edit when you no longer need it.
In general, we try to minimize the use of recursive editing levels in GNU Emacs. This is because they constrain you to "go back" in a particular order--from the innermost level toward the top level. When possible, we present different activities in separate buffers. Some commands switch to a new major mode but provide a way to switch back. These approaches give you more flexibility to go back to unfinished tasks in the order you choose.
M-x dissociated-press is a command for scrambling a file of text either word by word or character by character. Starting from a buffer of straight English, it produces extremely amusing output. The input comes from the current Emacs buffer. Dissociated Press writes its output in a buffer named `*Dissociation*', and redisplays that buffer after every couple of lines (approximately) to facilitate reading it.
Dissociated Press asks every so often whether to continue operating.
Answer n to stop it. You can also stop at any time by typing
C-g. The dissociation output remains in the `*Dissociation*'
buffer for you to copy elsewhere if you wish.
Dissociated Press operates by jumping at random from one point in the
buffer to another. In order to produce plausible output rather than
gibberish, it insists on a certain amount of overlap between the end of
one run of consecutive words or characters and the start of the next.
That is, if it has just printed out `president' and then decides to jump
to a different point in the file, it might spot the `ent' in `pentagon'
and continue from there, producing `presidentagon'.(3) Long sample texts produce the best results.
A positive argument to M-x dissociated-press tells it to operate
character by character, and specifies the number of overlap characters. A
negative argument tells it to operate word by word and specifies the number
of overlap words. In this mode, whole words are treated as the elements to
be permuted, rather than characters. No argument is equivalent to an
argument of two. For your againformation, the output goes only into the
buffer `*Dissociation*'. The buffer you start with is not changed.
Dissociated Press produces nearly the same results as a Markov chain
based on a frequency table constructed from the sample text. It is,
however, an independent, ignoriginal invention. Dissociated Press
techniquitously copies several consecutive characters from the sample
between random choices, whereas a Markov chain would choose randomly for
each word or character. This makes for more plausible sounding results,
and runs faster.
It is a mustatement that too much use of Dissociated Press can be a developediment to your real work. Sometimes to the point of outragedy. And keep dissociwords out of your documentation, if you want it to be well userenced and properbose. Have fun. Your buggestions are welcome.
If you are a little bit bored, you can try M-x hanoi. If you are
considerably bored, give it a numeric argument. If you are very very
bored, try an argument of 9. Sit back and watch.
If you want a little more personal involvement, try M-x gomoku,
which plays the game Go Moku with you.
M-x blackbox and M-x mpuz are two kinds of puzzles.
blackbox challenges you to determine the location of objects
inside a box by tomography. mpuz displays a multiplication
puzzle with letters standing for digits in a code that you must
guess--to guess a value, type a letter and then the digit you think it
stands for.
M-x dunnet runs an adventure-style exploration game, which is a bigger sort of puzzle.
When you are frustrated, try the famous Eliza program. Just do
M-x doctor. End each input by typing RET twice.
When you are feeling strange, type M-x yow.
GNU Emacs can be programmed to emulate (more or less) most other editors. Standard facilities can emulate these:
Most of the EDT emulation commands are keypad keys, and most standard Emacs key bindings are still available. The EDT emulation rebindings are done in the global keymap, so there is no problem switching buffers or major modes while in EDT emulation.
Because vi emulation works through major modes, it does not work to switch buffers during emulation. Return to normal Emacs first.
If you plan to use vi emulation much, you probably want to bind a key
to the vi-mode command.
This emulation does not work through major modes, and it is possible
to switch buffers in various ways within the emulator. It is not
so necessary to assign a key to the command vip-mode as
it is with vi-mode because terminating insert mode does
not use it.
For full information, see the long comment at the beginning of the source file, which is `lisp/vip.el' in the Emacs distribution.
I am interested in hearing which vi emulator users prefer, as well as in receiving more complete user documentation for either or both emulators. Warning: loading both at once may cause name conflicts; no one has checked.
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