# Vim documentation: autocmd

main help file

    *autocmd.txt*   For Vim version 6.0av.  Last change: 2001 Sep 03

    		  VIM REFERENCE MANUAL    by Bram Moolenaar

    Automatic commands					*autocommand*

    For a basic explanation, see section |40.3| in the user manual.

    1.  Introduction		|autocmd-intro|
    2.  Defining autocommands	|autocmd-define|
    3.  Removing autocommands	|autocmd-remove|
    4.  Listing autocommands	|autocmd-list|
    5.  Events			|autocmd-events|
    6.  Patterns			|autocmd-patterns|
    7.  Groups			|autocmd-groups|
    8.  Executing autocommands	|autocmd-execute|
    9.  Using autocommands		|autocmd-use|

    {Vi does not have any of these commands}

    ==============================================================================

    1. Introduction						*autocmd-intro*

    You can specify commands to be executed automatically for when reading or
    writing a file, when entering or leaving a buffer or window, and when exiting
    Vim.  For example, you can create an autocommand to set the 'cindent' option
    for files matching *.c.  You can also use autocommands to implement advanced
    features, such as editing compressed files (see |gzip-example|).  The usual
    place to put autocommands is in your .vimrc or .exrc file.

    							*E203* *E204* *E143*
    WARNING: Using autocommands is very powerful, and may lead to unexpected side
    effects.  Be careful not to destroy your text.
    - It's a good idea to do some testing on an expendable copy of a file first.
      For example: If you use autocommands to decompress a file when starting to
      edit it, make sure that the autocommands for compressing when writing work
      correctly.
    - Be prepared for an error halfway through (e.g., disk full).  Vim will mostly
      be able to undo the changes to the buffer, but you may have to clean up the
      changes to other files by hand (e.g., compress a file that has been
      decompressed).
    - If the BufRead* events allow you to edit a compressed file, the FileRead*
      events should do the same (this makes recovery possible in some rare cases).
      It's a good idea to use the same autocommands for the File* and Buf* events
      when possible.

    The |+autocmd| feature is only included if it has not been disabled at compile
    time.

    ==============================================================================

    2. Defining autocommands				*autocmd-define*

    Note: The ":autocmd" command cannot be followed by another command, since any
    '|' is considered part of the command.

    							*:au* *:autocmd*
    :au[tocmd] [group] {event} {pat} [nested] {cmd}
    			Add {cmd} to the list of commands that Vim will
    			execute automatically on {event} for a file matching
    			{pat}.  Vim always adds the {cmd} after existing
    			autocommands, so that the autocommands execute in the
    			order in which they were given.  See |autocmd-nested|
    			for [nested].

    Note that special characters (e.g., "%", "<cword>") in the ":autocmd"
    arguments are not expanded when the autocommand is defined.  These will be
    expanded when the Event is recognized, and the {cmd} is executed.  The only
    exception is that "<sfile>" is expanded when the autocmd is defined.  Example:

    	:au BufNewFile,BufRead *.html so <sfile>:h/html.vim

    Here Vim expands <sfile> to the name of the file containing this line.

    When your .vimrc file is sourced twice, the autocommands will appear twice.
    To avoid this, put this command in your .vimrc file, before defining
    autocommands:

    	:autocmd!	" Remove ALL autocommands for the current group.

    If you don't want to remove all autocommands, you can instead use a variable
    to ensure that Vim includes the autocommands only once:

    	:if !exists("autocommands_loaded")
    	:  let autocommands_loaded = 1
    	:  au ...
    	:endif

    When the [group] argument is not given, Vim uses the current group (as defined
    with ":augroup"); otherwise, Vim uses the group defined with [group].  Note
    that [group] must have been defined before.  You cannot define a new group
    with ":au group ..."; use ":augroup" for that.

    While testing autocommands, you might find the 'verbose' option to be useful:
    	:set verbose=9
    This setting makes Vim echo the autocommands as it executes them.

    When defining an autocommand in a script, it will be able to call functions
    local to the script and use mappings local to the script.  When the event is
    triggered and the command executed, it will run in the context of the script
    it was defined in.  This matters if |<SID>| is used in a command.

    When executing the commands, the messages from one command overwrites a
    previous message.  This is different from when executing the commands
    manually.  Mostly the screen will not scroll up, thus there is no hit-enter
    prompt.  When one command outputs two messages this can happen anyway.

    ==============================================================================

    3. Removing autocommands				*autocmd-remove*

    :au[tocmd]! [group] {event} {pat} [nested] {cmd}
    			Remove all autocommands associated with {event} and
    			{pat}, and add the command {cmd}.  See
    			|autocmd-nested| for [nested].

    :au[tocmd]! [group] {event} {pat}
    			Remove all autocommands associated with {event} and
    			{pat}.

    :au[tocmd]! [group] * {pat}
    			Remove all autocommands associated with {pat} for all
    			events.

    :au[tocmd]! [group] {event}
    			Remove ALL autocommands for {event}.

    :au[tocmd]! [group]	Remove ALL autocommands.

    When the [group] argument is not given, Vim uses the current group (as defined
    with ":augroup"); otherwise, Vim uses the group defined with [group].

    ==============================================================================

    4. Listing autocommands					*autocmd-list*

    :au[tocmd] [group] {event} {pat}
    			Show the autocommands associated with {event} and
    			{pat}.

    :au[tocmd] [group] * {pat}
    			Show the autocommands associated with {pat} for all
    			events.

    :au[tocmd] [group] {event}
    			Show all autocommands for {event}.

    :au[tocmd] [group]	Show all autocommands.

    If you provide the [group] argument, Vim lists only the autocommands for
    [group]; otherwise, Vim lists the autocommands for ALL groups.  Note that this
    argument behavior differs from that for defining and removing autocommands.

    ==============================================================================

    5. Events					*autocmd-events* *E215* *E216*

    					*autocommand-events* *{event}*
    Vim recognizes the following events.  Vim ignores the case of event names
    (e.g., you can use "BUFread" or "bufread" instead of "BufRead").

    							*BufNewFile*
    BufNewFile			When starting to edit a file that doesn't
    				exist.  Can be used to read in a skeleton
    				file.

    						*BufReadPre* *E200* *E201*
    BufReadPre			When starting to edit a new buffer, before
    				reading the file into the buffer.  Not used
    				if the file doesn't exist.

    						*BufRead* *BufReadPost*
    BufRead or BufReadPost		When starting to edit a new buffer, after
    				reading the file into the buffer, before
    				executing the modelines.  This does NOT work
    				for ":r file".  Not used when the file doesn't
    				exist.  Also used after successfully recovering
    				a file.

    							*BufReadCmd*
    BufReadCmd			Before starting to edit a new buffer.  Should
    				read the file into the buffer. |Cmd-event|

    							*BufFilePre*
    BufFilePre			Before changing the name of the current buffer
    				with the ":file" command.

    							*BufFilePost*
    BufFilePost			After changing the name of the current buffer
    				with the ":file" command.

    							*FileReadPre*
    FileReadPre			Before reading a file with a ":read" command.

    							*FileReadPost*
    FileReadPost			After reading a file with a ":read" command.
    				Note that Vim sets the '[ and '] marks to the
    				first and last line of the read.  This can be
    				used to operate on the lines just read.

    							*FileReadCmd*
    FileReadCmd			Before reading a file with a ":read" command.
    				Should do the reading of the file. |Cmd-event|

    							*FilterReadPre* *E135*
    FilterReadPre			Before reading a file from a filter command.
    				Vim checks the pattern against the name of
    				the current buffer, not the name of the
    				temporary file that is the output of the
    				filter command.

    							*FilterReadPost*
    FilterReadPost			After reading a file from a filter command.
    				Vim checks the pattern against the name of
    				the current buffer as with FilterReadPre.

    							*FileType*
    FileType			When the 'filetype' option has been set.
    				<afile> can be used for the name of the file
    				where this option was set, and <amatch> for
    				the new value of 'filetype'.
    				See |filetypes|.

    							*Syntax*
    Syntax				When the 'syntax' option has been set.
    				<afile> can be used for the name of the file
    				where this option was set, and <amatch> for
    				the new value of 'syntax'.
    				See |:syn-on|.

    							*StdinReadPre*
    StdinReadPre			Before reading from stdin into the buffer.
    				Only used when the "-" argument was used when
    				Vim was started |--|.

    							*StdinReadPost*
    StdinReadPost			After reading from the stdin into the buffer,
    				before executing the modelines.  Only used
    				when the "-" argument was used when Vim was
    				started |--|.

    						*BufWrite* *BufWritePre*
    BufWrite or BufWritePre		Before writing the whole buffer to a file.

    							*BufWritePost*
    BufWritePost			After writing the whole buffer to a file
    				(should undo the commands for BufWritePre).

    							*BufWriteCmd*
    BufWriteCmd			Before writing the whole buffer to a file.
    				Should do the writing of the file and reset
    				'modified' if successful.  The buffer contents
    				should not be changed.  |Cmd-event|

    							*FileWritePre*
    FileWritePre			Before writing to a file, when not writing the
    				whole buffer.

    							*FileWritePost*
    FileWritePost			After writing to a file, when not writing the
    				whole buffer.

    							*FileWriteCmd*
    FileWriteCmd			Before writing to a file, when not writing the
    				whole buffer.  Should do the writing to the
    				file.  Should not change the buffer.
    				|Cmd-event|

    							*FileAppendPre*
    FileAppendPre			Before appending to a file.

    							*FileAppendPost*
    FileAppendPost			After appending to a file.

    							*FileAppendCmd*
    FileAppendCmd			Before appending to a file.  Should do the
    				appending to the file. |Cmd-event|

    							*FilterWritePre*
    FilterWritePre			Before writing a file for a filter command or
    				making a diff.
    				Vim checks the pattern against the name of
    				the current buffer, not the name of the
    				temporary file that is the output of the
    				filter command.

    							*FilterWritePost*
    FilterWritePost			After writing a file for a filter command or
    				making a diff.
    				Vim checks the pattern against the name of
    				the current buffer as with FilterWritePre.

    							*FileChangedShell*
    FileChangedShell		When Vim notices that the modification time of
    				a file has changed since editing started.
    				|timestamp|
    				Mostly triggered after executing a shell
    				command, but also with a |:checktime| command
    				or when Vim regains input focus.
    				This autocommand is triggered for each changed
    				file.  It is not used when 'autoread' is set
    				and the buffer was not changed.  If a
    				FileChangedShell autocommand is present the
    				warning message and prompt is not given.
    				This is useful for reloading related buffers
    				which are affected by a single command.
    				NOTE: When this autocommand is executed, the
    				current buffer "%" may be different from the
    				buffer that was changed "<afile>".
    				NOTE: The commands must not change the current
    				buffer, jump to another buffer or delete a

    				buffer.  *E246*
    				NOTE: This event never nests, to avoid an
    				endless loop.

    							*FileChangedRO*
    FileChangedRO			Before making the first change to a read-only
    				file.  Can be used to check-out the file from
    				a source control system.  Not triggered when
    				the change was caused by an autocommand.
    				WARNING: This event is triggered when making a
    				change, just before the change is applied to
    				the text.  If the autocommand moves the cursor
    				the effect of the change is undefined.

    							*FocusGained*
    FocusGained			When Vim got input focus.  Only for the GUI
    				version and a few console versions where this
    				can be detected.

    							*FocusLost*
    FocusLost			When Vim lost input focus.  Only for the GUI
    				version and a few console versions where this
    				can be detected.

    							*FuncUndefined*
    FuncUndefined			When a user function is used but it isn't
    				defined.  Useful for defining a function only
    				when it's used.  Both <amatch> and <afile> are
    				set to the name of the function.

    							*CursorHold*
    CursorHold			When the user doesn't press a key for the time
    				specified with 'updatetime'.  Not re-triggered
    				until the user has pressed a key (i.e. doesn't
    				fire every 'updatetime' ms if you leave Vim to
    				make some coffee. :)  See |CursorHold-example|
    				for previewing tags.
    				Note: Interactive commands cannot be used for
    				this event.  There is no hit-enter prompt,
    				the screen is updated directly (when needed).
    				Note: In the future there will probably be
    				another option to set the time.
    				Hint: to force an update of the status lines
    				use:
    					:let &ro = &ro
     				{only on Amiga, Unix, Win32, MSDOS and all GUI
    				versions}

    							*BufEnter*
    BufEnter			After entering a buffer.  Useful for setting
    				options for a file type.  Also executed when
    				starting to edit a buffer, after the
    				BufReadPost autocommands.

    							*BufLeave*
    BufLeave			Before leaving to another buffer.  Also when
    				leaving or closing the current window and the
    				new current window is not for the same buffer.
    				Not used for ":qa" or ":q" when exiting Vim.

    							*BufWinEnter*
    BufWinEnter			After a buffer is displayed in a window.  This
    				can be when the buffer is loaded (after
    				processing the modelines), when a hidden
    				buffer is displayed in a window (and is no
    				longer hidden) or a buffer already visible in
    				a window is also displayed in another window.

    							*BufWinLeave*
    BufWinLeave			Before a buffer is removed from a window.
    				Not when it's still visible in another window.
    				Also triggered when exiting.  It's triggered
    				before BufUnload or BufHidden.
    				NOTE: When this autocommand is executed, the
    				current buffer "%" may be different from the
    				buffer being unloaded "<afile>".

    							*BufUnload*
    BufUnload			Before unloading a buffer.  This is when the
    				text in the buffer is going to be freed.  This
    				may be after a BufWritePost and before a
    				BufDelete.  Also used for all buffers that are
    				loaded when Vim is going to exit.
    				NOTE: When this autocommand is executed, the
    				current buffer "%" may be different from the
    				buffer being unloaded "<afile>".

    							*BufHidden*
    BufHidden			Just after a buffer has become hidden.  That
    				is, when there are no longer windows that show
    				the buffer, but the buffer is not unloaded or
    				deleted.  Not used for ":qa" or ":q" when
    				exiting Vim.
    				NOTE: When this autocommand is executed, the
    				current buffer "%" may be different from the
    				buffer being unloaded "<afile>".

    							*BufNew*
    BufNew				Just after creating a new buffer.  Also used
    				just after a buffer has been renamed.  When
    				the buffer is added to the buffer list BufAdd
    				will be triggered too.
    				NOTE: When this autocommand is executed, the
    				current buffer "%" may be different from the
    				buffer being created "<afile>".

    							*BufCreate* *BufAdd*
    BufAdd or BufCreate		Just after creating a new buffer which is
    				added to the buffer list, or adding a buffer
    				to the buffer list.
    				Also used just after a buffer in the buffer
    				list has been renamed.
    				The BufCreate event is for historic reasons.
    				NOTE: When this autocommand is executed, the
    				current buffer "%" may be different from the
    				buffer being created "<afile>".

    							*BufDelete*
    BufDelete			Before deleting a buffer from the buffer list.
    				The BufUnload may be called first (if the
    				buffer was loaded).
    				Also used just before a buffer in the buffer
    				list is renamed.
    				NOTE: When this autocommand is executed, the
    				current buffer "%" may be different from the
    				buffer being deleted "<afile>".

    							*BufWipeout*
    BufWipeout			Before completely deleting a buffer.  The
    				BufUnload and BufDelete events may be called
    				first (if the buffer was loaded and was in the
    				buffer list).  Also used just before a buffer
    				is renamed (also when it's not in the buffer
    				list).
    				NOTE: When this autocommand is executed, the
    				current buffer "%" may be different from the
    				buffer being deleted "<afile>".

    							*WinEnter*
    WinEnter			After entering another window.  Not done for
    				the first window, when Vim has just started.
    				Useful for setting the window height.
    				If the window is for another buffer, Vim
    				executes the BufEnter autocommands after the
    				WinEnter autocommands.

    							*WinLeave*
    WinLeave			Before leaving a window.  If the window to be
    				entered next is for a different buffer, Vim
    				executes the BufLeave autocommands before the
    				WinLeave autocommands (but not for ":new").
    				Not used for ":qa" or ":q" when exiting Vim.

    							*CmdwinEnter*
    CmdwinEnter			After entering the command-line window.
    				Useful for setting options specifically for
    				this special type of window.  This is
    				triggered _instead_ of BufEnter and WinEnter.
    				<afile> is set to a single character,
    				indicating the type of command-line.
    				|cmdwin-char|

    							*CmdwinLeave*
    CmdwinLeave			Before leaving the command-line window.
    				Useful to clean up any global setting done
    				with CmdwinEnter.  This is triggered _instead_
    				of BufLeave and WinLeave.
    				<afile> is set to a single character,
    				indicating the type of command-line.
    				|cmdwin-char|

    							*GUIEnter*
    GUIEnter			After starting the GUI successfully, and after
    				opening the window.  It is triggered before
    				VimEnter when using gvim.  Can be used to
    				position the window from a .gvimrc file:
    	:autocmd GUIEnter * winpos 100 50

     							*VimEnter*
    VimEnter			After doing all the startup stuff, including
    				loading .vimrc files, executing the "-c cmd"
    				arguments, creating all windows and loading
    				the buffers in them.

    							*VimLeavePre*
    VimLeavePre			Before exiting Vim, just before writing the
    				.viminfo file.  This is executed only once,
    				if there is a match with the name of what
    				happens to be the current buffer when exiting.
    				Mostly useful with a "*" pattern.
    	:autocmd VimLeavePre * call CleanupStuff()

     							*VimLeave*
    VimLeave			Before exiting Vim, just after writing the
    				.viminfo file.  Executed only once, like
    				VimLeavePre.

    							*EncodingChanged*
    EncodingChanged			Fires off when the 'encoding' option is
    				changed.  Useful to set up fonts, for example.

    							*FileEncoding*
    FileEncoding			Obsolete.  It still works and is equivalent
    				to |EncodingChanged|.

    							*RemoteReply*
    RemoteReply			When a reply from a Vim that functions as
    				server was received |server2client()|.
    				<amatch> is equal to the {serverid} from which
    				the reply was sent, and <afile> is the actual
    				reply string.
    				Note that even if an auto command is defined,
    				the reply should be read with |remote_read()|
    				to consume it.

    							*TermChanged*
    TermChanged			After the value of 'term' has changed.  Useful
    				for re-loading the syntax file to update the
    				colors, fonts and other terminal-dependent
    				settings.  Executed for all loaded buffers.

    							*TermResponse*
    TermResponse			After the response to |t_RV| is received from
    				the terminal.  The value of |v:termresponse|
    				can be used to do things depending on the
    				terminal version.

    							*UserGettingBored*
    UserGettingBored		When the user hits CTRL-C.  Just kidding! :-)

    							*User*
    User				Never executed automatically.  To be used for
    				autocommands that are only executed with
    				":doautocmd".

    For READING FILES there are three possible pairs of events.  Vim uses only one
    pair at a time:
    BufNewFile			starting to edit a non-existent file
    BufReadPre	BufReadPost	starting to edit an existing file
    FilterReadPre	FilterReadPost	read the temp file with filter output
    FileReadPre	FileReadPost	any other file read

    Note that the autocommands for the *ReadPre events and all the Filter events
    are not allowed to change the current buffer (you will get an error message if
    this happens).  This is to prevent the file to be read into the wrong buffer.

    Note that the 'modified' flag is reset AFTER executing the BufReadPost
    and BufNewFile autocommands.  But when the 'modified' option was set by the
    autocommands, this doesn't happen.

    You can use the 'eventignore' option to ignore a number of events or all
    events.

    ==============================================================================

    6. Patterns						*autocmd-patterns*

    The file pattern {pat} is tested for a match against the file name in one of
    two ways:
    1. When there is no '/' in the pattern, Vim checks for a match against only
       the tail part of the file name (without its leading directory path).
    2. When there is a '/' in the pattern,  Vim checks for a match against the
       both short file name (as you typed it) and the full file name (after
       expanding it to a full path and resolving symbolic links).

    Examples:
    	:autocmd BufRead *.txt		set et
    Set the 'et' option for all text files.

    	:autocmd BufRead /vim/src/*.c	set cindent
    Set the 'cindent' option for C files in the /vim/src directory.

    	:autocmd BufRead /tmp/*.c	set ts=5
    If you have a link from "/tmp/test.c" to "/home/nobody/vim/src/test.c", and
    you start editing "/tmp/test.c", this autocommand will match.

    Note:  To match part of a path, but not from the root directory, use a '*' as
    the first character.  Example:
    	:autocmd BufRead */doc/*.txt	set tw=78
    This autocommand will for example be executed for "/tmp/doc/xx.txt" and
    "/usr/home/piet/doc/yy.txt".  The number of directories does not matter here.

    The file name that the pattern is matched against is after expanding
    wildcards.  Thus is you issue this command:
    	:e $ROOTDIR/main.$EXT
    The argument is first expanded to:
    	/usr/root/main.py
    Before it's matched with the pattern of the autocommand.  Careful with this
    when using events like FileReadCmd, the value of <amatch> may not be what you
    expect.

    Environment variables can be used in a pattern:
    	:autocmd BufRead $VIMRUNTIME/doc/*.txt  set expandtab
    And ~ can be used for the home directory (if $HOME is defined):
    	:autocmd BufWritePost ~/.vimrc   so ~/.vimrc
    	:autocmd BufRead ~archive/*      set readonly
    The environment variable is expanded when the autocommand is defined, not when
    the autocommand is executed.  This is different from the command!

    							*file-pattern*
    The pattern is interpreted like mostly used in file names:
    	*	matches any sequence of characters
    	?	matches any single character
    	\?	matches a '?'
    	.	matches a '.'
    	~	matches a '~'
    	,	separates patterns
    	\,	matches a ','
    	{ }	like \( \) in a |pattern|
    	,	inside { }: like \| in a |pattern||||
    	\	special meaning like in a |pattern|
    	[ch]	matches 'c' or 'h'

    Note that for all systems the '/' character is used for path separator (even
    MS-DOS and OS/2).  This was done because the backslash is difficult to use
    in a pattern and to make the autocommands portable across different systems.

    Matching with the pattern is done when an event is triggered.  Changing the
    buffer name in one of the autocommands, or even deleting the buffer, does not
    change which autocommands will be executed.  Example:

    	au BufEnter *.foo  bdel
    	au BufEnter *.foo  set modified

    This will delete the current buffer and then set 'modified' in what has become
    the current buffer instead.  Vim doesn't take into account that "*.foo"
    doesn't match with that buffer name.  It matches "*.foo" with the name of the
    buffer at the moment the event was triggered.

    ==============================================================================

    7. Groups						*autocmd-groups*

    Autocommands can be put together in a group.  This is useful for removing or
    executing a group of autocommands.  For example, all the autocommands for
    syntax highlighting are put in the "highlight" group, to be able to execute
    ":doautoall highlight BufRead" when the GUI starts.

    When no specific group is selected, Vim uses the default group.  The default
    group does not have a name.  You cannot execute the autocommands from the
    default group separately; you can execute them only by executing autocommands
    for all groups.

    Normally, when executing autocommands automatically, Vim uses the autocommands
    for all groups.  The group only matters when executing autocommands with
    ":doautocmd" or ":doautoall", or when defining or deleting autocommands.

    The group name can contain any characters except white space.  The group name
    "end" is reserved (also in uppercase).  The group name is case sensitive.

    							*:aug* *:augroup*
    :aug[roup] {name}		Define the autocmd group name for the
    				following ":autocmd" commands.  The name "end"
    				or "END" selects the default group.

    						*:augroup-delete* *E367*
    :aug[roup]! {name}		Delete the autocmd group {name}.  Don't use
    				this if there is still an autocommand using
    				this group!  This is not checked.

    To enter autocommands for a specific group, use this method:
    1. Select the group with ":augroup {name}".
    2. Delete any old autocommands with ":au!".
    3. Define the autocommands.
    4. Go back to the default group with "augroup END".

    Example:
    	:augroup uncompress
    	:  au!
    	:  au BufEnter *.gz	%!gunzip
    	:augroup END

    This prevents having the autocommands defined twice (e.g., after sourcing the
    .vimrc file again).

    ==============================================================================

    8. Executing autocommands				*autocmd-execute*

    Vim can also execute Autocommands non-automatically.  This is useful if you
    have changed autocommands, or when Vim has executed the wrong autocommands
    (e.g., the file pattern match was wrong).

    Note that the 'eventignore' option applies here too.  Events listed in this
    option will not cause any commands to be executed.

    						*:do* *:doautocmd* *E217*
    :do[autocmd] [group] {event} [fname]
    			Apply the autocommands matching [fname] (default:
    			current file name) for {event} to the current buffer.
    			You can use this when the current file name does not
    			match the right pattern, after changing settings, or
    			to execute autocommands for a certain event.
    			It's possible to use this inside an autocommand too,
    			so you can base the autocommands for one extension on
    			another extension.  Example:
    				:au Bufenter *.cpp so ~/.vimrc_cpp
    				:au Bufenter *.cpp doau BufEnter x.c
     			Be careful to avoid endless loops.  See
    			|autocmd-nested|.

    			When the [group] argument is not given, Vim executes
    			the autocommands for all groups.  When the [group]
    			argument is included, Vim executes only the matching
    			autocommands for that group.  Note: if you use an
    			undefined group name, Vim gives you an error message.

    						*:doautoa* *:doautoall*
    :doautoa[ll] [group] {event} [fname]
    			Like ":doautocmd", but apply the autocommands to each
    			loaded buffer.  Careful: Don't use this for
    			autocommands that delete a buffer, change to another
    			buffer or change the contents of a buffer; the result
    			is unpredictable.  This command is intended for
    			autocommands that set options, change highlighting,
    			and things like that.

    ==============================================================================

    9. Using autocommands					*autocmd-use*

    For WRITING FILES there are four possible sets of events.  Vim uses only one
    of these sets for a write command:

    BufWriteCmd	BufWritePre	BufWritePost	writing the whole buffer
    		FilterWritePre	FilterWritePost	writing to filter temp file
    FileAppendCmd	FileAppendPre	FileAppendPost	appending to a file
    FileWriteCmd	FileWritePre	FileWritePost	any other file write

    When there is a matching "*Cmd" autocommand, it is assumed it will do the
    writing.  No further writing is done and the other events are not triggered.
    |Cmd-event|

    Note that the *WritePost commands should undo any changes to the buffer that
    were caused by the *WritePre commands; otherwise, writing the file will have
    the side effect of changing the buffer.

    Before executing the autocommands, the buffer from which the lines are to be
    written temporarily becomes the current buffer.  Unless the autocommands
    change the current buffer or delete the previously current buffer, the
    previously current buffer is made the current buffer again.

    The *WritePre and *AppendPre autocommands must not delete the buffer from
    which the lines are to be written.

    The '[ and '] marks have a special position:
    - Before the *ReadPre event the '[ mark is set to the line just above where
      the new lines will be inserted.
    - Before the *ReadPost event the '[ mark is set to the first line that was
      just read, the '] mark to the last line.
    - Before executing the *WritePre and *AppendPre autocommands the '[ mark is
      set to the first line that will be written, the '] mark to the last line.
    Careful: '[ and '] change when using commands that change the buffer.

    In commands which expect a file name, you can use "<afile>" for the file name
    that is being read |:<afile>| (you can also use "%" for the current file
    name).  "<abuf>" can be used for the buffer number of the currently effective
    buffer.  This also works for buffers that doesn't have a name.  But it doesn't
    work for files without a buffer (e.g., with ":r file").

    							*gzip-example*
    Examples for reading and writing compressed files:
      :augroup gzip
      :  autocmd!
      :  autocmd BufReadPre,FileReadPre	*.gz set bin
      :  autocmd BufReadPost,FileReadPost	*.gz '[,']!gunzip
      :  autocmd BufReadPost,FileReadPost	*.gz set nobin
      :  autocmd BufReadPost,FileReadPost	*.gz execute ":doautocmd BufReadPost " . expand("%:r")
      :  autocmd BufWritePost,FileWritePost	*.gz !mv <afile> <afile>:r
      :  autocmd BufWritePost,FileWritePost	*.gz !gzip <afile>:r

      :  autocmd FileAppendPre		*.gz !gunzip <afile>
      :  autocmd FileAppendPre		*.gz !mv <afile>:r <afile>
      :  autocmd FileAppendPost		*.gz !mv <afile> <afile>:r
      :  autocmd FileAppendPost		*.gz !gzip <afile>:r
      :augroup END

    The "gzip" group is used to be able to delete any existing autocommands with
    ":autocmd!", for when the file is sourced twice.

    ("<afile>:r" is the file name without the extension, see |:_%:|)

    The commands executed for the BufNewFile, BufRead/BufReadPost, BufWritePost,
    FileAppendPost and VimLeave events do not set or reset the changed flag of the
    buffer.  When you decompress the buffer with the BufReadPost autocommands, you
    can still exit with ":q".  When you use ":undo" in BufWritePost to undo the
    changes made by BufWritePre commands, you can still do ":q" (this also makes
    "ZZ" work).  If you do want the buffer to be marked as modified, set the
    'modified' option.

    To execute Normal mode commands from an autocommand, use the ":normal"
    command.  Use with care!  If the Normal mode command is not finished, the user
    needs to type characters (e.g., after ":normal m" you need to type a mark
    name).

    If you want the buffer to be unmodified after changing it, reset the
    'modified' option.  This makes it possible to exit the buffer with ":q"
    instead of ":q!".

    							*autocmd-nested* *E218*
    By default, autocommands do not nest.  If you use ":e" or ":w" in an
    autocommand, Vim does not execute the BufRead and BufWrite autocommands for
    those commands.  If you do want this, use the "nested" flag for those commands
    in which you want nesting.  For example:
      :autocmd FileChangedShell *.c nested e!
    The nesting is limited to 10 levels to get out of recursive loops.

    It's possible to use the ":au" command in an autocommand.  This can be a
    self-modifying command!  This can be useful for an autocommand that should
    execute only once.

    There is currently no way to disable the autocommands.  If you want to write a
    file without executing the autocommands for that type of file, write it under
    another name and rename it with a shell command.

    Note: When reading a file (with ":read file" or with a filter command) and the
    last line in the file does not have an <EOL>, Vim remembers this.  At the next
    write (with ":write file" or with a filter command), if the same line is
    written again as the last line in a file AND 'binary' is set, Vim does not
    supply an <EOL>.  This makes a filter command on the just read lines write the
    same file as was read, and makes a write command on just filtered lines write
    the same file as was read from the filter.  For example, another way to write
    a compressed file:

      :autocmd FileWritePre *.gz   set bin|'[,']!gzip
      :autocmd FileWritePost *.gz  undo|set nobin

    							*autocommand-pattern*
    You can specify multiple patterns, separated by commas.  Here are some
    examples:

      :autocmd BufRead   *		set tw=79 nocin ic infercase fo=2croq
      :autocmd BufRead   .letter	set tw=72 fo=2tcrq
      :autocmd BufEnter  .letter	set dict=/usr/lib/dict/words
      :autocmd BufLeave  .letter	set dict=
      :autocmd BufRead,BufNewFile   *.c,*.h	set tw=0 cin noic
      :autocmd BufEnter  *.c,*.h	abbr FOR for (i = 0; i < 3; ++i)<CR>{<CR>}<Esc>O
      :autocmd BufLeave  *.c,*.h	unabbr FOR

    For makefiles (makefile, Makefile, imakefile, makefile.unix, etc.):

      :autocmd BufEnter  ?akefile*	set include=^s\=include
      :autocmd BufLeave  ?akefile*	set include&

    To always start editing C files at the first function:

      :autocmd BufRead   *.c,*.h	1;/^{

    Without the "1;" above, the search would start from wherever the file was
    entered, rather than from the start of the file.

    						*skeleton* *template*
    To read a skeleton (template) file when opening a new file:

      :autocmd BufNewFile  *.c	0r ~/vim/skeleton.c
      :autocmd BufNewFile  *.h	0r ~/vim/skeleton.h
      :autocmd BufNewFile  *.java	0r ~/vim/skeleton.java

    To insert the current date and time in a *.html file when writing it:

      :autocmd BufWritePre,FileWritePre *.html   ks|call LastMod()|'s
      :fun LastMod()
      :  if line("$") > 20
      :    let l = 20
      :  else
      :    let l = line("$")
      :  endif
      :  exe "1," . l . "g/Last modified: /s/Last modified: .*/Last modified: " .
      :  \ strftime("%Y %b %d")
      :endfun

    You need to have a line "Last modified: <date time>" in the first 20 lines
    of the file for this to work.  Vim replaces <date time> (and anything in the
    same line after it) with the current date and time.  Explanation:
    	ks		mark current position with mark 's'
    	call LastMod()  call the LastMod() function to do the work
    	's		return the cursor to the old position
    The LastMod() function checks if the file is shorter than 20 lines, and then
    uses the ":g" command to find lines that contain "Last modified: ".  For those
    lines the ":s" command is executed to replace the existing date with the
    current one.  The ":execute" command is used to be able to use an expression
    for the ":g" and ":s" commands.  The date is obtained with the strftime()
    function.  You can change its argument to get another date string.

    When entering :autocmd on the command-line, completion of events and command
    names may be done (with <Tab>, CTRL-D, etc.) where appropriate.

    Vim executes all matching autocommands in the order that you specify them.
    It is recommended that your first autocommand be used for all files by using
    "*" as the file pattern.  This means that you can define defaults you like
    here for any settings, and if there is another matching autocommand it will
    override these.  But if there is no other matching autocommand, then at least
    your default settings are recovered (if entering this file from another for
    which autocommands did match).  Note that "*" will also match files starting
    with ".", unlike Unix shells.

    						    *autocmd-searchpat*
    Autocommands do not change the current search patterns.  Vim saves the current
    search patterns before executing autocommands then restores them after the
    autocommands finish.  This means that autocommands do not affect the strings
    highlighted with the 'hlsearch' option.  Within autocommands, you can still
    use search patterns normally, e.g., with the "n" command.
    If you want an autocommand to set the search pattern, such that it is used
    after the autocommand finishes, use the ":let @/ =" command.
    The search-highlighting cannot be switched off with ":nohlsearch" in an
    autocommand.  Use the 'h' flag in the 'viminfo' option to disable search-
    highlighting when starting Vim.

    							*Cmd-event*
    When using one of the "*Cmd" events, the matching autocommands are expected to
    do the file reading or writing.  This can be used when working with a special
    kind of file, for example on a remote system.
    CAREFUL: If you use these events in a wrong way, it may have the effect of
    making it impossible to read or write the matching files!  Make sure you test
    your autocommands properly.  Best is to use a pattern that will never match a
     normal file name, for example "ftp://*".

    When defining a BufReadCmd it will be difficult for Vim to recover a crashed
    editing session.  When recovering from the original file, Vim reads only those
    parts of a file that are not found in the swap file.  Since that is not
    possible with a BufReadCmd, use the |:preserve| command to make sure the
    original file isn't needed for recovery.  You might want to do this only when
    you expect the file to be modified.

    The |v:cmdarg| variable holds the "++enc=" and "++ff=" argument that are
    effective.  These should be used for the command that reads/writes the file.

    See the $VIMRUNTIME/plugin/netrw.vim for examples.

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