This manual is for Eat (version 0.9.4, 15 December 2023), a terminal emulator for Emacs.
Copyright © 2022, 2023 Akib Azmain Turja.
Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.3 or any later version published by the Free Software Foundation; with no Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts. A copy of the license is included in the section entitled “GNU Free Documentation License”.
Next: Hello Terminal, Up: Eat Manual [Contents][Index]
Eat (Emulate A Terminal) is a terminal emulator for Emacs. It emulates a XTerm-like terminal, just like many other terminal emulators. But it has some key features that make Eat distinct from other terminal emulators.
Firstly, it’s in Emacs, which means you don’t need to leave the comfort of Emacs to use terminal.
Secondly, it’s easy and convenient to use. It is tries to stay out of your way, allowing you to maximize your productivity.
Finally, special care has been taken while designing the keybindings, so that the terminal doesn’t conflict with Emacs default keybindings on both graphical display and text display, while still allowing you to run full screen programs like Emacs within the terminal.
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The terminal can be started with M-x eat. It’ll create a terminal and run the default shell (see Interactive Shell in GNU Emacs Manual) in it. You should get a shell prompt and be able to write shell commands and execute them. Full screen programs like ‘htop’, ‘lynx’ and Emacs will work inside it, just like any other terminal. (If the terminal doesn’t work as expected, see Common Problems.)
If an Eat terminal already exists, M-x eat will switch to it. To create a new terminal, call it with a prefix argument like this, C-u M-x eat.
If you give it a numeric prefix argument N, for example C-u 42 M-x eat, it’ll switch to a terminal in the buffer *eat*<N>, *eat*<42> for example, or it’ll create a new terminal if that buffer doesn’t exist.
If you give it double prefix argument, for example C-u C-u M-x eat, you’ll be prompted for the program or shell command to run, and it’ll be run in a newly created terminal.
Next: Eshell Terminal Emulation, Previous: Hello Terminal, Up: Eat Manual [Contents][Index]
Usually, you don’t use a single terminal for everything, instead you
open a terminal for each project that needs it. So there is command
named eat-project. It opens a new terminal in project root
directory, or switches to a already existing project terminal. It too
accepts prefix argument, just like the ordinary eat command.
Next: Keyboard, Previous: Project-local Terminal, Up: Eat Manual [Contents][Index]
Eat also supports terminal emulation outside Eat’s terminal. So you can emulate terminal in Eshell (see Eshell manual) with Eat. After configuring Eshell to use Eat for terminal emulation, you can run any full screen terminal program in Eshell.
To enable terminal emulation in Eshell, enable the global minor mode
eat-eshell-mode. It will enable Eat’s terminal emulation in
Eshell. To disable the terminal emulation, disable the minor mode.
You can’t toggle the global minor mode while any Eshell command is running, so terminate any Eshell command or wait them to finish before toggling the mode.
Unless stated otherwise, everything described in this manual about Eat terminal also applies to Eshell terminal emulation.
You might also want to set eshell-visual-commands user option
to nil, since they’ll work in Eshell when eat-eshell-mode is
enabled.
If you want to run Eshell visual commands with Eat, you can enable the
global minor mode eat-eshell-visual-command-mode.
Next: Mouse, Previous: Eshell Terminal Emulation, Up: Eat Manual [Contents][Index]
Just like any other text terminal, the primary interaction device with Eat terminal is the keyboard. Eat forwards all supported keyboard events like a, E, RET, C-a to the terminal.
However, this conflict with Emacs keybinding conventions, and makes it almost impossible to call any other Emacs command. So, by default, Eat doesn’t intercept the key sequences beginning with the following keys and lets Emacs to handle them: C-\, C-c, C-x, C-g, C-h, C-M-c, C-u, C-q, M-x, M-:, M-! and M-&.
To input the above key sequences, prefix them with C-q. C-q reads the next event and sends to directly to the terminal. For example, to input M-:, use the key sequence C-q M-:.
For an alternative way to input these exceptional characters, see Char Mode.
Next: Input Modes, Previous: Keyboard, Up: Eat Manual [Contents][Index]
Eat supports mouse tracking. That means in programs like Emacs, ‘htop’, etc, that support mouse, you can hover and click on text and buttons. You can also use your mouse wheel to scroll text, if the program supports it.
See Mouse Tracking to configure mouse tracking.
Next: Password Input, Previous: Mouse, Up: Eat Manual [Contents][Index]
By default, Eat forwards all supported keys to terminals, except some exceptions. It is possible to input them with C-q, but it is not very convenient.
To conveniently input those character, they should be bound to input themselves to the terminal (i.e. pressing M-x will input M-x, bypassing Emacs). But this is conflicts with Emacs’s default keybindings, so this can’t done, at least by default.
To overcome the problem, Eat implements several “input modes”. Each input mode has a different set of keybindings for different applications.
“Semi-char mode” is the default input mode of Eat. This works for most inputs. It forwards all keys, except C-\, C-c, C-x, C-g, C-h, C-M-c, C-u, M-x, C-q, M-:, M-!, M-& and some other keys, Emacs handles them.
To input these exceptions, there is a key C-q. This reads the next input event and sends that as the input. For example, the key sequences C-q M-: inputs M-:, C-q C-g inputs C-g.
Input methods (see Input Methods in GNU Emacs Manual) work in this mode, so, unlike Term (see Emacs Terminal Emulator in GNU Emacs Manual), Emacs built-in terminal emulator, you can still input any character.
In “semi-char mode”, C-c C-c sends a C-c, just for convenience, and C-c C-k kills the terminal program.
You can customize the exceptions by customizing the user option
eat-semi-char-non-bound-keys, and
eat-eshell-semi-char-non-bound-keys for Eshell integration.
Both user options contain a list of keys of form [key],
where key is a key not to bind. key mustn’t contain meta
modifier. To not bind a key with meta modifier, use a vector of form
[?\e key], where key is the key without meta
modifier. These user options contain all the “semi-char” mode
exceptions listed above, plus some more exceptions.
If you set the user options manually (for example, with setq),
you must call eat-update-semi-char-mode-map or
eat-eshell-update-semi-char-mode-map respectively, and finally
reload Eat (you can do this with the command eat-reload).
Or alternatively you can set the user options before Eat is loaded.
By default, Eat is in “semi-char mode”. In this input mode, Eat forwards all supported keys to terminals, except some exceptions, see Semi-char Mode. It is possible to input them with C-q, but it is not very convenient.
To overcome this problem, Eat implements another input mode called
“char mode”. To switch to “char mode”, press C-c M-d in
“semi-char mode”. In Eshell, the command
eshell-toggle-direct-send is remapped to enable
“char-mode”, which is usually bound to C-c M-d.
In this input mode, Eat forwards all supported keys. However, input methods still work in this mode, so you can still input keys that are not on your keyboard.
To get out of “char mode”, press C-M-m or M-RET, this switches back to “semi-char mode”.
In “emacs mode”, no input events are send to the terminal. In this mode, you can interact with the terminal buffer just like a regular buffer. However, you are not allowed to change the buffer contents.
To switch to “emacs mode”, press C-c C-e from “semi-char mode”.
In this mode, C-c C-k kills the terminal program like in “semi-char mode”.
From “emacs mode”, you can switch to “semi-char mode” with
C-c C-j and to “char mode” with C-c M-d. In Eshell, the
command eshell-toggle-direct-send is remapped to enable
“char-mode”, which is usually bound to C-c M-d.
In “line mode”, input is sent one line at a line, similar to Comint or Shell mode (see Interactive Shell in GNU Emacs Manual). Like “emacs mode”, you can interact with buffer as you wish; but at the very end of the buffer, you can edit the input line with usual Emacs commands. This is not available in Eshell.
To enter “line mode”, press C-c C-l from “semi-char mode” or “emacs mode”.
RET sends the current input with a trailing newline, and clear the input area for new input to be written. When called with a prefix argument, no newline is appended before sending input. To input a newline character without actually sending it, you can press C-c SPC.
C-c C-c discards the input completely and sends an interrupt to the terminal. C-d deletes the character after the point, or sends EOF if the input is empty.
You can’t modify the terminal in “line mode”, you can write only in
the input line. Eat automatically moves the point to the input line
if you try to insert character in the terminal region. This behavior
can be disabled by customizing eat-line-auto-move-to-input to
nil.
You can exit to “emacs mode”, “semi-char mode” or “char mode” with C-c C-e, C-c C-j or C-c M-d respectively. If there’s any pending input when exiting line mode, it is sent as is to the terminal.
The input history is recorded. You can cycle through the history with M-p and M-n, and also with C-up and C-down. C-c M-r and C-c M-s searches the input history taking the current input as the query. C-c M-r searches backward while C-c M-s searches forward. And C-c C-r searches the input history using minibuffer with completion, useful specially if you use any minibuffer completion UI/framework.
You can also use Isearch
(see Incremental Search in GNU Emacs Manual) to search
through the input history, with M-r. You can also customize
eat-line-input-history-isearch to use all standard Isearch
commands to search the input history.
Controls where Isearch searches in Eat buffer. If t, usual
Isearch commands in Eat buffer search in the input history. If
dwim, Isearch keys search in the input history only when
initial point position is on input line. When starting Isearch from
other parts of the Eat buffer, they search in the Eat buffer. If
nil, Isearch operates on the whole Eat buffer.
Input history is not loaded from the shell history file, to do that, See Line Mode Integration.
Next: Shell Integration, Previous: Input Modes, Up: Eat Manual [Contents][Index]
By default, every keystroke gets recorded in the lossage, which can be seen by pressing C-h l. This is actually a good thing, unless you’re inputting password.
Emacs doesn’t record keystrokes when a password is read from the
minibuffer. However, when the password prompt is in the terminal, the
keys you use to type in your password gets recorded. To prevent this
from happening, you can use the command eat-send-password,
it’ll read password from the minibuffer and send it. Since the
password is read from the minibuffer, it’s not recorded.
Next: Querying Before Kill, Previous: Password Input, Up: Eat Manual [Contents][Index]
Eat comes with shell scripts to integrate your favorite shell with Eat. When shell integration is enabled and the script is loaded in your shell, it’ll take care of everything and provide many useful features.
Currently only GNU Bash and Zsh are supported.
If you use GNU Bash, put the following in your ‘.bashrc’ file:
[ -n "$EAT_SHELL_INTEGRATION_DIR" ] && \ source "$EAT_SHELL_INTEGRATION_DIR/bash"
If you use Zsh, put the following in your ‘.zshrc’ file:
[ -n "$EAT_SHELL_INTEGRATION_DIR" ] && \ source "$EAT_SHELL_INTEGRATION_DIR/zsh"
After you’ve setup shell integration, the Eat will track the working
directory of your shell. That means find-file will start
from your shell’s current working directory. This also works in
Eshell, but after the program exits, the current working directory is
changed back to the directory from where the program was invoked.
This controls directory tracking. When set to non-nil, Eat
tracks the current working directory of programs.
When shell integration is setup, Eat annotates each shell prompt. Eat puts a mark on the shell prompt indicating the whether the command entered in that prompt is running, exited successfully or exited with non-zero status. This doesn’t work in Eshell. You can disable this feature if you want.
This controls shell prompt annotation by Eat. When set to
non-nil, Eat annotates shell prompts to indicate the status of
the command entered in that prompt.
Eat uses the marginal area (see Display Margins in GNU Emacs Lisp Reference Manual) on the left side to display the annotation. You also use the right margin.
This controls where the shell prompt annotations are displayed. When
set to left-margin (the default), Eat uses the left margin.
When set to right-margin, Eat uses the right margin.
Eat uses the strings “-”, “0” and “X” respectively to indicate
the command is running, the command has succeeded and the command has
failed. You can also customize the them. The user option
eat-shell-prompt-annotation-running-margin-indicator and the
face eat-shell-prompt-annotation-running control the indicator
used to indicate the command is running. The user option
eat-shell-prompt-annotation-success-margin-indicator and the
face eat-shell-prompt-annotation-success control the indicator
used to indicate the command has exited successfully. And finally
the user option
eat-shell-prompt-annotation-failure-margin-indicator and the
face eat-shell-prompt-annotation-failure control the indicator
used to indicate the command has exited unsuccessfully with non-zero
exit status.
After enabling shell integration, you can send messages to Emacs from your shell. Then you can handle the message on Emacs side using usual Emacs Lisp function.
When shell integration script is loaded, a function named
_eat_msg is defined in your shell. You can use this to send
any message to Emacs. (The ‘_’ in the beginning of the function
name is intentional to prevent shadowing any actual command.)
Send message message, handled by the handler named handler-name in Emacs.
The messages are handled with the handlers defined in
eat-message-handler-alist.
Alist of message handler name and its handler function. The keys are
the names of message handlers (i.e. the handler-name argument of
_eat_msg), and the values are their respective handler
functions. The handler function is called with the message
arguments of _eat_msg. Messages with undefined handlers are
ignored. To disable message passing, set this to nil.
Beware, messages can be sent by malicious and/or buggy programs running in the shell, therefore you should always verify the message before doing anywhere.
When shell integration is enabled, the input history of line mode is automatically filled with the shell history when the shell starts. Also you can make Eat automatically switch to “line mode” (see Line Mode) for you when the shell prompt appears.
When non-nil, automatically switch to line mode the shell prompt appears.
Next: Changing the Default Shell, Previous: Shell Integration, Up: Eat Manual [Contents][Index]
When a terminal is killed, the terminal process is also killed. Since
the process can do some important things, Eat asks for confirmation
before killing a terminal with running process by default. Eat
provides the user option
eat-query-before-killing-running-terminal to control this.
When set to nil, Eat would never ask. When set to t,
Eat would always ask for confirmation. When set to auto, Eat
would ask only if a shell command is running inside the shell running
in the terminal. This is effective only after shell integration is
enabled in the shell (see Shell Integration) (i.e. after the shell
integration code is executed on shell); before that it is essentially
same as t, and Eat will always query.
Next: Display, Previous: Querying Before Kill, Up: Eat Manual [Contents][Index]
Eat automatically uses a reasonable shell by default. However you can customize it.
The default shell to run.
This user options allows you to customize default shell for each Tramp method. It’s an alist and it’s elements are of form (TRAMP-METHOD SHELL).
This user options gives more control on the default shell. It specifies a function to call without any argument, whose return value is used as the default shell.
If you change this from the default value, eat-shell and
eat-tramp-shells won’t work.
Next: Scrollback, Previous: Changing the Default Shell, Up: Eat Manual [Contents][Index]
Display is the region you see on the terminal. The program writes to the display and manipulates the text on the display. The display can be of any size. The cursor is always on the display (though it might be invisible sometimes, see Cursor Types).
You can resize the display by resizing the terminal window. The
display size is controlled by the Emacs user option
window-adjust-process-window-size-function. See Process
Buffers in GNU Emacs Lisp Reference Manual for the possible
values of the user option.
Next: Cursor Types, Previous: Display, Up: Eat Manual [Contents][Index]
When you go too downward on the terminal, the terminal starts to “scroll”. This causes the line at the upper side of the terminal to go out of the display and become hidden. But these line are not deleted, they are just put in the scrollback region.
Scrollback region is a region just above the display of the terminal. This contains the lines that went out of display due to scrolling up.
Scrollback region is not unlimited by default, to avoid using too much memory. You can change the limit, or remove it altogether.
This controls the size of scrollback region. It is expressed in
character. If set to size, Eat won’t store more than size
characters in the scrollback region. If set to nil, the
scrollback region is unlimited.
Next: Mouse Tracking, Previous: Scrollback, Up: Eat Manual [Contents][Index]
In terminal, cursor can be of up to three type: “visible”, “invisible” and “very visible”. “Visible” is the default cursor type, which is the cursor you usually see in a shell (unless the shell changes the cursor type). “Invisible” is, as the name suggests, invisible, you can’t see it. “Very visible” cursor is a blinking cursor, programs use this to help you not lose the cursor.
The cursor type can customized with three user options for the three types of cursor. Each of the user options share the same format.
This controls the cursor shape of the “visible” cursor type.
This controls the cursor shape of the “invisible” cursor type.
This controls the cursor shape of the “very visible” cursor type. This cursor blinks, switching between the default cursor shape and a hollow box.
This controls the cursor shape of the “vertical bar” cursor type.
This controls the cursor shape of the “very visible vertical bar” cursor type. This cursor blinks.
This controls the cursor shape of the “horizontal bar” cursor type.
This controls the cursor shape of the “very visible horizontal bar” cursor type. This cursor blinks.
The value type of all these user options is a list. The list is of
form (cursor-on blinking-frequency cursor-off).
blinking-frequency is the frequency of blinking of cursor. It
is a number, controlling how many times the cursor will blink a
second. This can also be nil, this will disable cursor
blinking. cursor-on is the default cursor shape, only this
shape is shown on the display when blinking is disabled. This uses
the same format as Emacs’s cursor-type user option
(see Cursor Display in GNU Emacs Manual). When
blinking-frequency is a number, Eat will consult to the third
element of the list, cursor-off, whose format same as
cursor-on. The blinking cursor switches between cursor-on
and cursor-off cursor shape.
Next: Clipboard, Previous: Cursor Types, Up: Eat Manual [Contents][Index]
Eat tracks mouse by default, when the program supports mouse. But sometimes, you may want to avoid using mouse, or you might not have a mouse at all. So mouse tracking can be toggled.
This user option controls mouse tracking. When set to non-nil,
mouse tracking is enabled. Set to this to nil to disable mouse
tracking. This is enabled by default.
Next: Colors, Previous: Mouse Tracking, Up: Eat Manual [Contents][Index]
Just like any other buffer, you can yank text in terminal with
C-y (bound to eat-yank) or M-y (bound to
eat-yank-pop) in “semi-char mode”.
Programs can also request to the terminal to kill (see Killing in GNU Emacs Manual) something. It is up to Eat whether the request will be fulfilled or not. By default, Eat fulfills the request and kills the text. This can sometimes be annoying, when the program automatically kills text without user interaction. This killing can be configured with the following user option:
This controls killing texts from terminal. When set to
non-nil, killing something from terminal add the text to
Emacs’s kill ring (see Kill Ring in GNU Emacs Manual).
This is enabled by default.
Programs can also request the text in kill ring. Again, this is up to Eat whether the request will be fulfilled or not. You can customize the following user option to configure this:
This controls sending kill ring texts to terminal. When set to
non-nil, programs can receive the kill ring contents. This is
disabled by default for security reasons.
Next: Fonts, Previous: Clipboard, Up: Eat Manual [Contents][Index]
Eat can show more than 16 million colors (16,777,216 colors exactly). Eat has also a palette of 256 colors, which is more than enough for most applications. Programs usually use this color palette. Each of these 256 colors can customized.
There are 256 faces for the 256 colors, one face for each color. They
are named like eat-term-color-n, which corresponds to
color n, and n can be any number between 0 and 255
(inclusive). For example, color 42 is can be changed by customizing
eat-term-color-42.
The foreground attribute contains the color value to use for the corresponding color. Other attributes are currently ignored and reserved for future changes.
Each of the first 16 colors, from eat-term-color-0 to
eat-term-color-15 also have a alias. They are respectively
eat-term-color-black,
eat-term-color-red,
eat-term-color-green,
eat-term-color-yellow,
eat-term-color-blue,
eat-term-color-magenta,
eat-term-color-cyan,
eat-term-color-white,
eat-term-color-bright-black,
eat-term-color-bright-red,
eat-term-color-bright-green,
eat-term-color-bright-yellow,
eat-term-color-bright-blue,
eat-term-color-bright-magenta,
eat-term-color-bright-cyan
and eat-term-color-bright-white.
Eat also supports 24-bit colors, or so called “truecolor”. Programs like Emacs can give a RGB triplet to use as the color of some text. As the programs directly specify the color in this case, you can’t customize these color. But you may configure the program sending the color codes.
Eat doesn’t always advertise color support depending on the display Eat is running. For example, if you are on a Linux console which supports only eight colors, Eat will advertise eight color support to the programs, while on graphical displays with 24-bit color support, Eat will report 24-bit color support. This is because Eat supports more colors, the display doesn’t always support them.
Eat does the trick by setting the TERM environment variable of
the program. The value of TERM depends on the number of the
available colors on the display. This environment variable is
controlled by the following user option:
The value of TERM environment variable as a string. The value
can also be a function taking no arguments, that function should
return a string which used as the value of TERM. The default
value is eat-term-get-suitable-term-name, which is responsible
for the behavior described above.
Next: Sixel, Previous: Colors, Up: Eat Manual [Contents][Index]
Programs may request the terminal to change the text font. It can change text weight, use italic text, or even change the font family altogether.
Programs may request the terminal to show some text bolder than
normal. Bold text uses the face eat-term-bold.
Programs may also request the terminal to show some text fainter than
normal. Faint text uses the face eat-term-faint.
Programs may request the terminal to show italic text too. Italic
text uses the customizable face eat-term-italic.
The number of available fonts is ten. Most of the programs doesn’t change the font. Following many other terminal emulator, Eat actually uses the same font, the default font, regardless of the font requested by the program, by default.
There are ten faces for ten fonts, one face for each. They are named
like eat-term-font-n, which corresponds to color n,
and n can be any number between 0 and 9 (inclusive). For
example, the font 6 is can be changed by customizing
eat-term-font-6. Font 0 is the default font.
Next: Blinking Text, Previous: Fonts, Up: Eat Manual [Contents][Index]
Eat can show Sixel graphics. Sixel is a bitmap graphics format that can be used to display graphics in a terminal, for example, images, or plotting graphs.
You can control the display of Sixel images by customizing the following user options.
This is a non-negative number that specifies the amount to scale the image by.
This is a non-negative number that specifies the aspect ratio, i.e. the ratio of width and height of a Sixel pixel. For example, the value of 2 means the width of a Sixel pixel is the double of its height.
Eat converts Sixel graphics to an image format Emacs can natively
display. This preference of image formats can be configured by
customizing the eat-sixel-render-formats user option.
List of formats to render Sixel, in order of preference. Each element
of the list is one of xpm, svg, half-block,
background, none. xpm and svg means to
use XPM and SVG image format respectively, half-block means to
use UTF-8 half block characters, background means to just use
background color, and none means to not render the image,
instead just clear the area.
Next: Performance Tuning, Previous: Sixel, Up: Eat Manual [Contents][Index]
Programs can request the terminal to blink some text. This helps to get user attention. But however, often this annoying to many people and also has accessiblity problems. So this is disabled by default.
This controls the blinking of text with blink attribute. When set to
non-nil, Eat arranges that text with blink attribute will
blink at a certain interval.
You can toggle blinking temporarily by toggle the buffer-local minor
mode eat-blink-mode. This is only effective in the buffer
where the mode is toggled.
By default, eat-enable-blinking-text is set to nil.
This disables text blinking and causes the text with blink attribute
to be displayed in inverse video (swapped foreground and background).
Programs may also request to blink some text more rapidly that other
blinking text. When blinking is disabled, the face
eat-term-slow-blink is used for slowly blinking text, and
eat-term-fast-blink for rapidly blinking text.
When blinking is enabled, by setting eat-enable-blinking-text
to non-nil value, the following user options can be customized
to change the rate of blinking:
The blinking rate of slowly blinking text. When set to a number N, it causes slowly blinking text to blink N times a second. The value can also be a floating point number. The default value is 2, meaning that the slowing text will blink two times a second.
The blinking rate of rapidly blinking text. When set to a number N, it causes rapidly blinking text to blink N times a second. The value can also be a floating point number as well. The default value is 3, meaning that the slowing text will blink three times a second.
Next: Common Problems, Previous: Blinking Text, Up: Eat Manual [Contents][Index]
Eat tries to be as fast as possible. So Eat employs some techniques to maximize performance.
Some program choke and hang when given too much input at once. So Eat
divides large input to smaller chunks and sends the chunks one at a
time. The maximum size of a input chunk is controlled by
eat-input-chunk-size.
The value is a integer. Eat treat input larger than this many character as large and breaks it into chunks of at most this size before sending the input.
Programs also break large output into smaller chunks before sending it to the terminal, for same reason. Eat doesn’t suffer from the problem, but there isn’t any standard way to inform programs about this, and usually there are other obstructions sending large amount of data at once. These small chunks create another problem for Eat, flickering. When updating the whole display, the output is usually pretty large and the programs break them into smaller chunks. Each of the chunks update the display partially. After receiving the last chunk, the update is complete and the display can be updated. But it is impossible for Eat to guess the last chunk, so Eat has to redisplay or update the display after receiving each chunk. This is the reason why sometimes the terminal shows some old contents and some new. This only lasts for a fraction of a second until the next chunk is received and processed. This is flickering. This also degrades performance, because redisplay is an expensive process and takes some time.
Fixing the flickering completely is not possible. Eat tries to decrease flickering by deferring redisplay. After receiving a chunk, Eat waits for a tiny fraction of a second. If another chunk arrives within the time, the redisplay is postponed. Then Eat waits for the same amount of time and this goes on. When timeout occurs, Eat processing the output and displays the output. This causes a small latency between output arrive and redisplay, but this is usually not long enough for human eyes to catch it. This waiting time can be configured with the following user option:
The value is the time in seconds to wait for the next chunk to arrive. This is the minimum latency between the first chunk after a redisplay and the next redisplay. For example, if you press RET in an empty Bash prompt, the next prompt won’t appear before this much time.
You should set the time to something comfortable for you. You can also set this to zero to disable waiting and showing the output instantly, but this would likely cause a lot of flickering.
However, this waiting raises another problem. What if you execute the POSIX command ‘yes’ in the terminal? It will write infinite “y”s in the terminal without any delay between them anywhere. Eat will wait indefinitely for a delay between two chunks, which will never happen, unless the program is executed remotely and the connection is slow enough. So Eat has a limit for waiting, the display will be always be updated after this time. This limit also customizable:
The value is the time in seconds to wait at most for chunk. In case of large burst of output, redisplay is never deferred more than this many seconds, and cause a latency of up to this many seconds.
You should set the time to something comfortable for you. You can also set this to zero to disable waiting and showing the output instantly, but this would likely cause a lot of flickering.
Due to some limitations, shell prompt annotations (see Shell Integration) can get messed up sometimes. Eat automatically corrects them after each terminal redisplay. However, this can have some performance impact when the terminal scrollback and display is large enough (unless the buffer is narrowed). So Eat defers the correction.
The value is the time in seconds to wait for more output before correcting shell prompt annotations.
You should set the time to something comfortable for you. You can also set this to zero to disable waiting and correct annotations instantly, but this may cause the terminal to slow down in some cases.
The user options described in this chapter have reasonable default values, but the default values may change anytime.
Next: Reporting Bugs, Previous: Performance Tuning, Up: Eat Manual [Contents][Index]
This chapter describe how to recognize and handle situations in which Eat does something unexpected, such as hangs, garbled text, etc.
Next: Garbled Text on Terminal, Up: Common Problems [Contents][Index]
If your program says that it can’t recognize the terminal, probably
the TERM environment variable has a wrong value.
Check the value of TERM, if it’s not set to something like
‘eat-...’, check the user option eat-term-name. If that’s
correct that your shell might be changing the TERM environment
variable. If eat-term-name isn’t correct, customize to a
suitable value and try again, your problem should be fixed.
If TERM has the correct value, then probably the Terminfo
databases of Eat are missing. This can happen if you have installed
Eat without using the package from NonGNU ELPA
(see Packages in GNU Emacs Manual). Check that whether
the values of the environment variable TERMINFO and the user
option eat-term-terminfo-directory match. If they match,
customize eat-term-terminfo-directory to the directory
containing the Terminfo databases, the program should now recognize
Eat. If they don’t match, then your shell is probably responsible for
the problem.
If the program is not recognizing the terminal even when
the correct directory is set as eat-term-terminfo-directory,
probably the precompiled Terminfo databases aren’t working properly on
your system. You can invoke the command
eat-compile-terminfo to recompile it for your system.
If you can’t find the directory containing Terminfo databases, you can
compile it yourself. First, set eat-term-terminfo-directory to
the directory where to put the Terminfo databases. Then invoke the
command eat-compile-terminfo to compile the Terminfo
databases.
Next: Input Invisible, Previous: Terminal Not Recognized, Up: Common Problems [Contents][Index]
If the text on the terminal looks wrong, first check out the value of
TERM. Usually TERM has a wrong value set, making programs
send invalid escape sequences.
First, see Terminal Not Recognized; the problem is most likely because the program doesn’t recognize Eat, and it stays silent instead of reporting that.
If the problem isn’t resolved after following the instructions in the
previous section, probably the precompiled Terminfo databases aren’t
working properly on your system. Running the command
eat-compile-terminfo will recompile it for your system.
If the problem still persists, may be your program is blindly assuming that the terminal is XTerm-compatible. If so, what you are seeing is the current state of “XTerm-compliance”. Though it’s not really a bug, we really want to know what’s problem so that we can fix it and improve XTerm-compliance. See Reporting Bugs for instructions on sending bug reports or feature request.
The other potential reason is that Eat is not working. This is definitely a bug, so please report it.
Next: Emacs or Eat Not Responding, Previous: Garbled Text on Terminal, Up: Common Problems [Contents][Index]
This can happen if the ‘stty’ program is unavailable on the system. Eat uses ‘stty’ to set various terminal settings including input echoing. Please install the ‘stty’ program to fix the problem.
If you are using Eat from Eshell (see Eshell Terminal Emulation), you might
want to set eat-eshell-fallback-if-stty-not-available to handle
such cases. The user option can be set to three possible value,
t to automatically fallback to bare Eshell when ‘stty’ is
not available, nil to do nothing, and ‘ask’ to ask
interactively.
Next: Eat Signaled an Error, Previous: Input Invisible, Up: Common Problems [Contents][Index]
If you run something that outputs huge amount of data, your Emacs may not respond, and even quitting may not work. Quitting doesn’t work while doing something terminal related (output processing, for example), and that’s intentional, because quitting would mess up the terminal.
The best way to fix it is to stop the program, so that Eat is not overloaded. To avoid the problem in future, it is recommended to run those programs in faster terminals like bare Eshell (i.e. without Eat-Eshell), Comint, or external terminal emulators.
Next: Bugs in Manual, Previous: Emacs or Eat Not Responding, Up: Common Problems [Contents][Index]
The worst thing that happen is that Eat might signal an error. It is the worst thing possible, because it messes up the terminal, and also a security hole. Fortunately, this is very rare. If you ever find any such bug, you should report the bug (see Reporting Bugs) as soon as possible with as much information as possible.
Once the error signaled, your best option is to delete the terminal
and start a new one. But if you don’t want to delete the terminal,
you can try invoking the command reset from your shell. If
for some reason you can’t do that, invoke the Emacs command
eat-reset. This will reset most of the terminal state and
give you a clean terminal to work with. However, it mayn’t work if
you’re really unlucky, in that case deleting the terminal and starting
a new one is your only option.
Previous: Eat Signaled an Error, Up: Common Problems [Contents][Index]
Human makes mistake, and we are no exceptions. But we are trying hard to improve Eat and it’s manual.
If you don’t understand something even after a careful rereading, that’s a bug.
If you find anything unclear in this manual, that’s a bug.
This manual’s job is make everything clear, so failing to do that indicates a bug.
If the built-in documentation and this manual don’t agree, one of them must be wrong, and that’s a bug.
If you Eat doesn’t behave as this manual describes, that’s a bug.
If you find any typing mistakes, that’s a bug.
If you find a bug, please report it. See Reporting Bugs for instruction on how to report it.
Next: Tracing the Terminal, Previous: Common Problems, Up: Eat Manual [Contents][Index]
We welcome bug reports and feature request. If you think you have found a bug, please report it. If you’re doubt, please send it anyway. We can’t promise that we’ll fix the bug or implement your feature idea, or always agree that it’s a bug, but we always want to hear from you. Please report bugs at https://codeberg.org/akib/emacs-eat/issues/. You may send the bug report by emailing to the maintainer (M-x describe-package RET eat RET would show the email address), but we prefer the former method, since the report is visible to everyone immediately.
The most important principle in reporting a bug is to report facts. Hypotheses and verbal descriptions are useful when they are more guesses, but in no way substitute for detailed raw data. You are encouraged to send you finding about bug, but please make sure to send the raw data needed to reproduce the bug.
For bug reports, please try to reproduce the bug with ‘emacs -Q’. This will disable loading your Emacs configuration, ruling out the potential bugs in your customizations. Please include enough information for us to reproduce the bug with ‘emacs -Q’, so that we have (or can get) enough information about the bug to fix it. Some bugs are hard to reproduce with ‘emacs -Q’, and some are not easily reproducible at all, in that case please give us the as much information as possible about Emacs configuration. Generally speaking, enough information includes (but not limited to):
emacs -Q, as much
information as possible about Emacs configuration.
When in doubt whether to include something or not, please include it. It is better to include many useless information than to leave out something useful.
It is critical to send enough information to reproduce the bug. What is not critical to “narrow down” the example to the smallest possible – anything that reproduces the bug will suffice. (Of course, if you like doing experiments, the smaller the example, the better.)
Next: GNU General Public License, Previous: Reporting Bugs, Up: Eat Manual [Contents][Index]
When you run into a bug and want to report it, you’ll want to trace the terminal. Tracing means recording all the terminal activity, including creation, output, resizing and deleting.
To enable tracing, enable the global minor mode
eat-trace-mode. This will trace all new terminals,
including the terminal created inside Eshell.
Trace output for each command will be output in a buffer named ‘*eat-trace buffer-name*: command’, where buffer-name is the buffer showing the terminal, and command is the command run in the terminal.
Only the terminals created after the trace mode is enabled are traced. So if you don’t have the mode enabled when you have found a bug, tracing can’t give you any information (as tracing is disabled, nothing has been recorded).
While submitting bug reports, please include the whole output in the trace output buffer. This contains many crucial information required to reproduce your bug.
You can replay the terminal by executing the command
eat-trace-replay is the trace output buffer. You can use
the key n or the key down to show the next frame.
This is not intended for ordinary users, it’s documented here only to
help you debug Eat. You mustn’t rely on the behavior of this
functionality to do anything else.
Next: GNU Free Documentation License, Previous: Tracing the Terminal, Up: Eat Manual [Contents][Index]
Copyright © 2007 Free Software Foundation, Inc. https://fsf.org/ Everyone is permitted to copy and distribute verbatim copies of this license document, but changing it is not allowed.
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one line to give the program's name and a brief idea of what it does. Copyright (C) year name of author This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with this program. If not, see https://www.gnu.org/licenses/.
Also add information on how to contact you by electronic and paper mail.
If the program does terminal interaction, make it output a short notice like this when it starts in an interactive mode:
program Copyright (C) year name of author This program comes with ABSOLUTELY NO WARRANTY; for details type ‘show w’. This is free software, and you are welcome to redistribute it under certain conditions; type ‘show c’ for details.
The hypothetical commands ‘show w’ and ‘show c’ should show the appropriate parts of the General Public License. Of course, your program’s commands might be different; for a GUI interface, you would use an “about box”.
You should also get your employer (if you work as a programmer) or school, if any, to sign a “copyright disclaimer” for the program, if necessary. For more information on this, and how to apply and follow the GNU GPL, see https://www.gnu.org/licenses/.
The GNU General Public License does not permit incorporating your program into proprietary programs. If your program is a subroutine library, you may consider it more useful to permit linking proprietary applications with the library. If this is what you want to do, use the GNU Lesser General Public License instead of this License. But first, please read https://www.gnu.org/licenses/why-not-lgpl.html.
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Copyright © 2000, 2001, 2002, 2007, 2008 Free Software Foundation, Inc. https://fsf.org/ Everyone is permitted to copy and distribute verbatim copies of this license document, but changing it is not allowed.
The purpose of this License is to make a manual, textbook, or other functional and useful document free in the sense of freedom: to assure everyone the effective freedom to copy and redistribute it, with or without modifying it, either commercially or noncommercially. Secondarily, this License preserves for the author and publisher a way to get credit for their work, while not being considered responsible for modifications made by others.
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We have designed this License in order to use it for manuals for free software, because free software needs free documentation: a free program should come with manuals providing the same freedoms that the software does. But this License is not limited to software manuals; it can be used for any textual work, regardless of subject matter or whether it is published as a printed book. We recommend this License principally for works whose purpose is instruction or reference.
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If a section in the Document is Entitled “Acknowledgements”, “Dedications”, or “History”, the requirement (section 4) to Preserve its Title (section 1) will typically require changing the actual title.
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However, if you cease all violation of this License, then your license from a particular copyright holder is reinstated (a) provisionally, unless and until the copyright holder explicitly and finally terminates your license, and (b) permanently, if the copyright holder fails to notify you of the violation by some reasonable means prior to 60 days after the cessation.
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An MMC is “eligible for relicensing” if it is licensed under this License, and if all works that were first published under this License somewhere other than this MMC, and subsequently incorporated in whole or in part into the MMC, (1) had no cover texts or invariant sections, and (2) were thus incorporated prior to November 1, 2008.
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To use this License in a document you have written, include a copy of the License in the document and put the following copyright and license notices just after the title page:
Copyright (C) year your name. Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.3 or any later version published by the Free Software Foundation; with no Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts. A copy of the license is included in the section entitled ``GNU Free Documentation License''.
If you have Invariant Sections, Front-Cover Texts and Back-Cover Texts, replace the “with…Texts.” line with this:
with the Invariant Sections being list their titles, with
the Front-Cover Texts being list, and with the Back-Cover Texts
being list.
If you have Invariant Sections without Cover Texts, or some other combination of the three, merge those two alternatives to suit the situation.
If your document contains nontrivial examples of program code, we recommend releasing these examples in parallel under your choice of free software license, such as the GNU General Public License, to permit their use in free software.
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