MG(1)

NAME
mg - emacs-like text editor

SYNOPSIS
mg [-n] [-f mode] [+number] [file ...]

DESCRIPTION
mg is intended to be a small, fast, and portable editor for people who can't (or don't want to) run emacs for one reason or another, or are not familiar with the vi(1) editor. It is compatible with emacs because there shouldn't be any reason to learn more editor types than emacs or vi(1).

The options are as follows:

+number
    Go to the line specified by number (do not insert a space between the ‘+’ sign and the number). If a negative number is specified, the line number counts backwards from the end of the file i.e. +-1 will be the last line of the file, +-2 will be second last, and so on.

-f mode
    Run the mode command for all buffers created from arguments on the command line, including the scratch buffer and all files.

-n  Turn off backup file generation.

WINDOWS AND BUFFERS
When a file is loaded into mg, it is stored in a buffer. This buffer may be displayed on the screen in more than one window. At present, windows may only be split horizontally, so each window is delineated by a modeline at the bottom. If changes are made to a buffer, it will be reflected in all open windows.

If a buffer name begins and ends with an asterisk, the buffer is considered throwaway; i.e. the user will not be prompted to save changes when the buffer is killed.

POINT AND MARK
The current cursor location in mg is called the point (or dot). It is possible to define a window-specific region of text by setting a second location, called the mark. The region is the text between point and mark inclusive. Deleting the character at the mark position leaves the mark at the point of deletion.

Note: The point and mark are window-specific in mg, not buffer-specific, as in other emacs flavours.

BACKUP FILES
Backup files have a ‘~’ character appended to the file name and are created in the current working directory by default. Whether to create backup files or not can be toggled with the make-backup-file command. The backup file location can either be in the current working directory, or all backups can be moved to a ~/.mg.d directory where files retain their path name to retain uniqueness. Use the backup-to-home-directory to alternate between these two locations. Further, if any application creates backup files in the TMPDIR, these can be left with the leave-tmpdir-backups command.

TAGS
mg supports tag files created by ctags(1), allowing the user to quickly locate various object definitions. Note though that emacs uses etags, not ctags.

CSCOPE
mg supports navigating source code using cscope. However, mg requires cscope and cscope-indexer executables to be present in PATH for it to work.

DEFAULT KEY BINDINGS
Normal editing commands are very similar to GNU Emacs. In the following examples, C-x means Control-x, and M-x means Meta-x, where the Meta key may be either a special key on the keyboard or the ALT key; otherwise ESC followed by the key X works as well.

C-SPC
    set-mark-command
C-a beginning-of-line
C-b backward-char
C-c s c
    cscope-find-functions-calling-this-function
C-c s d
    cscope-find-global-definition
C-c s e
    cscope-find-egrep-pattern
C-c s f
    cscope-find-this-file
C-c s i
    cscope-find-files-including-file
C-c s n
    cscope-next-symbol
C-c s p
    cscope-prev-symbol
C-c s s
    cscope-find-this-symbol
C-c s t
    cscope-find-this-text-string
C-d delete-char
C-e end-of-line
C-f forward-char
C-g keyboard-quit
C-h C-h
    help-help
C-h a
    apropos
C-h b
    describe-bindings
C-h c
    describe-key-briefly
C-j newline-and-indent
C-k kill-line
C-l recenter
RET newline
C-n next-line
C-o open-line
C-p previous-line
C-q quoted-insert
C-r isearch-backward
C-s isearch-forward
C-t transpose-chars
C-u universal-argument
C-v scroll-up
C-w kill-region
C-x C-b
    list-buffers
C-x C-c
    save-buffers-kill-emacs
C-x C-f
    find-file
C-x C-g
    keyboard-quit
C-x C-l
    downcase-region
C-x C-o
    delete-blank-lines
C-x C-q
    toggle-read-only
C-x C-r
    find-file-read-only
C-x C-s
    save-buffer
C-x C-u
    upcase-region
C-x C-v
    find-alternate-file
C-x C-w
    write-file
C-x C-x
    exchange-point-and-mark
C-x (
    start-kbd-macro
C-x)
    end-kbd-macro
C-x 0
    delete-window
C-x 1
    delete-other-windows
C-x 2
    split-window-vertically
C-x 4 C-f
    find-file-other-window
C-x 4 C-g
    keyboard-quit
C-x 4 b
    switch-to-buffer-other-window
C-x 4 f
    find-file-other-window
C-x =
    what-cursor-position
C-x ^
    enlarge-window
C-x `
    next-error
C-x b
    switch-to-buffer
C-x d
    dired
C-x e
    call-last-kbd-macro
C-x f
    set-fill-column
C-x g
    goto-line
C-x h
    mark-whole-buffer
C-x i
    insert-file
C-x k
    kill-buffer
C-x n
    other-window
C-x o
    other-window
C-x p
    previous-window
C-x s
    save-some-buffers
C-x u
    undo
C-y yank
C-z suspend-emacs
M-C-v
    scroll-other-window
M-SPC
    just-one-space
M-. find-tag
M-* pop-tag-mark
M-% query-replace
M-< beginning-of-buffer
M-> end-of-buffer
M-\ delete-horizontal-space
M-^ join-line
M-b backward-word
M-c capitalize-word
M-d kill-word
M-f forward-word
M-l downcase-word
M-m back-to-indentation
M-q fill-paragraph
M-r search-backward
M-s search-forward
M-u upcase-word
M-v scroll-down
M-w copy-region-as-kill
M-x execute-extended-command
M-{ backward-paragraph
M-| shell-command-on-region
M-} forward-paragraph
M-~ not-modified
M-DEL
    backward-kill-word
C-_ undo
)   blink-and-insert
DEL delete-backward-char

For a complete description of mg commands, see MG COMMANDS. To see the active keybindings at any time, type “M-x describe-bindings”.

MG COMMANDS
Commands are invoked by “M-x”, or by binding to a key. Many commands take an optional numerical parameter, n. This parameter is set either by M-<n> (where n is the numerical argument) before the command, or by one or more invocations of the universal argument, usually bound to C-u. When invoked in this manner, the value of the numeric parameter to be passed is displayed in the minibuffer before the M-x. One common use of the parameter is in mode toggles (e.g. make-backup-files). If no parameter is supplied, the mode is toggled to its alternate state. If a positive parameter is supplied, the mode is forced to on. Otherwise, it is forced to off.

apropos
    Help Apropos. Prompt the user for a string, open the *help* buffer, and list all mg commands that contain that string.

auto-execute
    Register an auto-execute hook; that is, specify a filename pattern (conforming to the shell's filename globbing rules) and an associated function to execute when a file matching the specified pattern is read into a buffer.

auto-fill-mode
    Toggle auto-fill mode (sometimes called mail-mode), where text inserted past the fill column is automatically wrapped to a new line.

auto-indent-mode
    Toggle indent mode, where indentation is preserved after a newline.

back-to-indentation
    Move the dot to the first non-whitespace character on the current line.

backup-to-home-directory
    Save backup copies to a ~/.mg.d directory instead of working directory. Requires make-backup-files to be on.

backward-char
    Move cursor backwards one character.

backward-kill-word
    Kill text backwards by n words.

backward-paragraph
    Move cursor backwards n paragraphs. Paragraphs are delimited by <NL><NL> or <NL><TAB> or <NL><SPACE>.

backward-word
    Move cursor backwards by the specified number of words.

beginning-of-buffer
    Move cursor to the top of the buffer.

beginning-of-line
    Move cursor to the beginning of the line.

blink-and-insert
    Self-insert a character, then search backwards and blink its matching delimiter. For delimiters other than parenthesis, brackets, and braces, the character itself is used as its own match.

bsmap-mode
    Toggle bsmap mode, where DEL and C-h are swapped.

c-mode
    Toggle a KNF-compliant mode for editing C program files.

call-last-kbd-macro
    Invoke the keyboard macro.

capitalize-word
    Capitalize n words; i.e. convert the first character of the word to upper case, and subsequent letters to lower case.

cd  Change the global working directory. See also global-wd-mode.

copy-region-as-kill
    Copy all of the characters in the region to the kill buffer, clearing the mark afterwards. This is a bit like a kill-region followed by a yank.

count-matches
    Count the number of lines matching the supplied regular expression.

count-non-matches
    Count the number of lines not matching the supplied regular expression.

cscope-find-this-symbol
    List the matches for the given symbol.

cscope-find-global-definition
    List global definitions for the given literal.

cscope-find-called-functions
    List functions called from the given function.

cscope-find-functions-calling-this-function
    List functions calling the given function.

cscope-find-this-text-string
    List locations matching the given text string.

cscope-find-egrep-pattern
    List locations matching the given extended regular expression pattern.

cscope-find-this-file
    List filenames matching the given filename.

cscope-find-files-including-file
    List files that #include the given filename.

cscope-next-symbol
    Navigate to the next match.

cscope-prev-symbol
    Navigate to the previous match.

cscope-next-file
    Navigate to the next file.

cscope-prev-file
    Navigate to the previous file.

cscope-create-list-of-files-to-index
    Create cscope's List and Index in the given directory.

define-key
    Prompts the user for a named keymap (mode), a key, and an mg command, then creates a keybinding in the appropriate map.

delete-backward-char
    Delete backwards n characters. Like delete-char, this actually does a kill if presented with an argument.

delete-blank-lines
    Delete blank lines around dot. If dot is sitting on a blank line, this command deletes all the blank lines above and below the current line. Otherwise, it deletes all of the blank lines after the current line.

delete-char
    Delete n characters forward. If any argument is present, it kills rather than deletes, saving the result in the kill buffer.

delete-horizontal-space
    Delete any whitespace around the dot.

delete-leading-space
    Delete leading whitespace on the current line.

delete-trailing-space
    Delete trailing whitespace on the current line.

delete-matching-lines
    Delete all lines after dot that contain a string matching the supplied regular expression.

delete-non-matching-lines
    Delete all lines after dot that contain a string matching the supplied regular expression.

delete-other-windows
    Make the current window the only window visible on the screen.

delete-window
    Delete current window.

describe-bindings
    List all global and local keybindings, putting the result in the *help* buffer.

describe-key-briefly
    Read a key from the keyboard, and look it up in the keymap. Display the name of the function currently bound to the key.

digit-argument
    Process a numerical argument for keyboard-invoked functions.

downcase-region
    Set all characters in the region to lower case.

downcase-word
    Set characters to lower case, starting at the dot, and ending n words away.

emacs-version
    Return an mg version string.

end-kbd-macro
    Stop defining a keyboard macro.

end-of-buffer
    Move cursor to the end of the buffer.

end-of-line
    Move cursor to the end of the line.

enlarge-window
    Enlarge the current window by shrinking either the window above or below it.

eval-current-buffer
    Evaluate the current buffer as a series of mg commands. Useful for testing mg startup files.

eval-expression
    Get one line from the user, and run it. Useful for testing expressions in mg startup files.

exchange-point-and-mark
    Swap the values of "dot" and "mark" in the current window. Return an error if no mark is set.

execute-extended-command
    Invoke an extended command; i.e. M-x. Call the message line routine to read in the command name and apply autocompletion to it. When it comes back, look the name up in the symbol table and run the command if it is found, passing arguments as necessary. Print an error if there is anything wrong.

fill-paragraph
    Justify a paragraph, wrapping text at the current fill column.

find-file
    Select a file for editing. First check if the file can be found in another buffer; if it is there, just switch to that buffer. If the file cannot be found, create a new buffer, read in the file from disk, and switch to the new buffer.

find-file-read-only
    Same as find-file, except the new buffer is set to read-only.

find-alternate-file
    Replace the current file with an alternate one. Semantics for finding the replacement file are the same as find-file, except the current buffer is killed before the switch. If the kill fails, or is aborted, revert to the original file.

find-file-other-window
    Opens the specified file in a second buffer. Splits the current window if necessary.

find-tag
    Jump to definition of tag at dot.

forward-char
    Move cursor forwards (or backwards, if n is negative) n characters. Returns an error if the end of buffer is reached.

forward-paragraph
    Move forward n paragraphs. Paragraphs are delimited by <NL><NL> or <NL><TAB> or <NL><SPACE>.

forward-word
    Move the cursor forward by the specified number of words.

global-set-key
    Bind a key in the global (fundamental) key map.

global-unset-key
    Unbind a key from the global (fundamental) key map; i.e. set it to 'rescan'.

global-wd-mode
    Toggle global working-directory mode. When enabled, mg defaults to opening files (and executing commands like compile and grep) relative to the global working directory. When disabled, a working directory is set for each buffer.

goto-line
    Go to a specific line. If an argument is present, then it is the line number, else prompt for a line number to use.

help-help
    Prompts for one of (a)propos, (b)indings, des(c)ribe key briefly.

insert
    Insert a string, mainly for use from macros.

insert-buffer
    Insert the contents of another buffer at dot.

insert-file
    Insert a file into the current buffer at dot.

insert-with-wrap
    Insert the bound character with word wrap. Check to see if we're past the fill column, and if so, justify this line.

isearch-backward
    Use incremental searching, initially in the reverse direction. isearch ignores any explicit arguments. If invoked during macro definition or evaluation, the non-incremental search-backward is invoked instead.

isearch-forward
    Use incremental searching, initially in the forward direction. isearch ignores any explicit arguments. If invoked during macro definition or evaluation, the non-incremental search-forward is invoked instead.

join-line
    Join the current line to the previous. If called with an argument, join the next line to the current one.

just-one-space
    Delete any whitespace around dot, then insert a space.

keyboard-quit
    Abort the current action.

kill-buffer
    Dispose of a buffer, by name. If the buffer name does not start and end with an asterisk, prompt the user if the buffer has been changed.

kill-line
    Kill line. If called without an argument, it kills from dot to the end of the line, unless it is at the end of the line, when it kills the newline. If called with an argument of 0, it kills from the start of the line to dot. If called with a positive argument, it kills from dot forward over that number of newlines. If called with a negative argument it kills any text before dot on the current line, then it kills back abs(n) lines.

kill-paragraph
    Delete n paragraphs starting with the current one.

kill-region
    Kill the currently defined region.

kill-word
    Delete forward n words.

leave-tmpdir-backups
    Modifies the behaviour of backup-to-home-directory. Backup files that would normally reside in the system TMPDIR are left there and not moved to the ~/.mg.d directory.

line-number-mode
    Toggle whether line and column numbers are displayed in the modeline.

list-buffers
    Display the list of available buffers.

load
    Prompt the user for a filename, and then execute commands from that file.

local-set-key
    Bind a key mapping in the local (topmost) mode.

local-unset-key
    Unbind a key mapping in the local (topmost) mode.

make-backup-files
    Toggle generation of backup files.

mark-whole-buffer
    Marks whole buffer as a region by putting dot at the beginning and mark at the end of buffer.

meta-key-mode
    When disabled, the meta key can be used to insert extended-ascii (8-bit) characters. When enabled, the meta key acts as usual.

negative-argument
    Process a negative argument for keyboard-invoked functions.

newline
    Insert a newline into the current buffer.

newline-and-indent
    Insert a newline, then enough tabs and spaces to duplicate the indentation of the previous line. Assumes tabs are every eight characters.

next-line
    Move forward n lines.

no-tab-mode
    Toggle notab mode. In this mode, spaces are inserted rather than tabs.

not-modified
    Turn off the modified flag in the current buffer.

open-line
    Open up some blank space. Essentially, insert n newlines, then back up over them.

other-window
    The command to make the next (down the screen) window the current window. There are no real errors, although the command does nothing if there is only 1 window on the screen.

overwrite-mode
    Toggle overwrite mode, where typing in a buffer overwrites existing characters rather than inserting them.

prefix-region
    Inserts a prefix string before each line of a region. The prefix string is settable by using 'set-prefix-string'.

previous-line
    Move backwards n lines.

previous-window
    This command makes the previous (up the screen) window the current window. There are no errors, although the command does not do a lot if there is only 1 window.

pop-tag-mark
    Return to position where find-tag was previously invoked.

push-shell
    Suspend mg and switch to alternate screen, if available.

pwd Display current (global) working directory in the status area.

query-replace
    Query Replace. Search and replace strings selectively, prompting after each match.

replace-string
    Replace string globally without individual prompting.

query-replace-regexp
    Replace strings selectively. Does a search and replace operation using regular expressions for both patterns.

quoted-insert
    Insert the next character verbatim into the current buffer; i.e. ignore any function bound to that key.

re-search-again
    Perform a regular expression search again, using the same search string and direction as the last search command.

re-search-backward
    Search backwards using a regular expression. Get a search string from the user, and search, starting at dot and proceeding toward the front of the buffer. If found, dot is left pointing at the first character of the pattern [the last character that was matched].

re-search-forward
    Search forward using a regular expression. Get a search string from the user and search for it starting at dot. If found, move dot to just after the matched characters. display does all the hard stuff. If not found, it just prints a message.

recenter
    Reposition dot in the current window. By default, the dot is centered. If given a positive argument (n), the display is repositioned to line n. If n is negative, it is that line from the bottom.

redraw-display
    Refresh the display. Recomputes all window sizes in case something has changed.

save-buffer
    Save the contents of the current buffer if it has been changed, optionally creating a backup copy.

save-buffers-kill-emacs
    Offer to save modified buffers and quit mg.

save-some-buffers
    Look through the list of buffers, offering to save any buffer that has been changed. Buffers that are not associated with files (such as *scratch*, *grep*, *compile*) are ignored.

scroll-down
    Scroll backwards n pages. A two-line overlap between pages is assumed. If given a repeat argument, scrolls back lines, not pages.

scroll-one-line-down
    Scroll the display down n lines without changing the cursor position.

scroll-one-line-up
    Scroll the display n lines up without moving the cursor position.

scroll-other-window
    Scroll the next window in the window list window forward n pages.

scroll-up
    Scroll forward one page. A two-line overlap between pages is assumed. If given a repeat argument, scrolls back lines, not pages.

search-again
    Search again, using the same search string and direction as the last search command.

search-backward
    Reverse search. Get a search string from the user, and search, starting at dot and proceeding toward the front of the buffer. If found, dot is left pointing at the first character of the pattern (the last character that was matched).

search-forward
    Search forward. Get a search string from the user, and search for it starting at dot. If found, dot gets moved to just after the matched characters, if not found, print a message.

self-insert-command
    Insert a character.

set-case-fold-search
    Set case-fold searching, causing case not to matter in regular expression searches. This is the default.

set-default-mode
    Append the supplied mode to the list of default modes used by subsequent buffer creation. Built in modes include: fill, indent, overwrite, and notab.

set-fill-column
    Prompt the user for a fill column. Used by auto-fill-mode.

set-mark-command
    Sets the mark in the current window to the current dot location.

set-prefix-string
    Sets the prefix string to be used by the 'prefix-region' command.

shell-command-on-region
    Provide the text in region to the shell command as input.

shrink-window
    Shrink current window by one line. The window immediately below is expanded to pick up the slack. If only one window is present, this command has no effect.

space-to-tabstop
    Insert enough spaces to reach the next tab-stop position. By default, tab-stops occur every 8 characters.

split-window-vertically
    Split the current window. A window smaller than 3 lines cannot be split.

start-kbd-macro
    Start defining a keyboard macro. Macro definition is ended by invoking end-kbd-macro.

suspend-emacs
    Suspend mg and switch back to alternate screen, if in use.

switch-to-buffer
    Prompt and switch to a new buffer in the current window.

switch-to-buffer-other-window
    Switch to buffer in another window.

toggle-read-only
    Toggle the read-only flag on the current buffer.

transpose-chars
    Transpose the two characters on either side of dot. If dot is at the end of the line, transpose the two characters before it. Return with an error if dot is at the beginning of line; it seems to be a bit pointless to make this work.

undo
    Undo the most recent action. If invoked again without an intervening command, move the undo pointer to the previous action and undo it.

undo-boundary
    Add an undo boundary. This is not usually done interactively.

undo-boundary-toggle
    Toggle whether undo boundaries are generated. Undo boundaries are often disabled before operations that should be considered atomically undoable.

undo-enable
    Toggle whether undo information is kept.

undo-list
    Show the undo records for the current buffer in a new buffer.

universal-argument
    Repeat the next command 4 times. Usually bound to C-u. This command may be stacked; e.g. C-u C-u C-f moves the cursor forward 16 characters.

upcase-region
    Upper case region. Change all of the lower case characters in the region to upper case.

upcase-word
    Move the cursor forward by the specified number of words. As it moves, convert any characters to upper case.

visit-tags-table
    Record name of the tags file to be used for subsequent find-tag.

what-cursor-position
    Display a bunch of useful information about the current location of dot. The character under the cursor (in octal), the current line, row, and column, and approximate position of the cursor in the file (as a percentage) is displayed. The column position assumes an infinite position display; it does not truncate just because the screen does.

write-file
    Ask for a file name and write the contents of the current buffer to that file. Update the remembered file name and clear the buffer changed flag.

yank
    Yank text from kill-buffer. Unlike emacs, the mg kill buffer consists only of the most recent kill. It is not a ring.

CONFIGURATION FILES
There are two configuration files, .mg and .mg-TERM. Here, TERM represents the name of the terminal type; e.g. if the terminal type is set to “vt100”, mg will use .mg-vt100 as a startup file. The terminal type startup file is used first.

The startup file format is a list of commands, one per line, as used for interactive evaluation. Strings that are normally entered by the user at any subsequent prompts may be specified after the command name; e.g.:

    global-set-key ")" self-insert-command
    global-set-key "\^x\^f" find-file
    global-set-key "\e[Z" backward-char
    set-default-mode fill
    set-fill-column 72
    auto-execute *.c c-mode

FILES
~/.mg
    normal startup file
~/.mg-TERM
    terminal-specific startup file
~/.mg.d
    alternative backup file location
/usr/share/doc/mg/tutorial
    concise tutorial

SEE ALSO
ctags(1), vi(1)

CAVEATS
Since it is written completely in C, there is currently no language in which extensions can be written; however, keys can be rebound and certain parameters can be changed in startup files.

In order to use 8-bit characters (such as German umlauts), the Meta key needs to be disabled via the “meta-key-mode” command.