<< vim

Vim Autocmd

1. Create Autocommand

# General Format

The general format of autocmd are

:au[tocmd] [group] {event} {pat} [++once] [++nested] {cmd}

For those files meet pattern {pat}, when the event {event} is triggered, execute the command specified by {cmd}. Regex is supported in the pattern field.

For example

:autocmd BufRead *.txt      set expandtab

This will set expandtab, for all *.txt file when opened.

The common events include

• BufNewFile, starting to edit a file that doesn’t exist.
• BufRead, starting to edit a new buffer, after reading the file
• BufWrite, starting to write the whole buffer to a file.
• FileType, when the filetype option ahs been set.

You can refer the vim help autocmd for complete events list.

The event and pattern field can both be the comma separated list, for example, we usually want to execute the same process when create a new file or open an exist file, we use BufNewFile, BufRead to receive both events:

autocmd BufNewFile, BufRead *.proc set filetype=proc

The [++once] option makes the command one-shot, that is, will be removed right after the first execution.

2. List Autocommand

The commands

:au[tocmd] {event} {pat}
:au[tocmd] {event}
:au[tocmd] * {pat}

will list the autocommands that meet the corresponding event and/or pattern.

3. Execute Autocmmand

We can actively execute the command by

:do[autocmd] {event} [fname]

which will execute the autocommand given by the {event} and [fname]. By default, the parameter [fname] is the current filename. While this can also be applied when the current filename does not match the pattern but matched by [fname].

Notice that it is permitted to write a doautocmd in an autocmd, that is, we can create the autocommand for one pattern based on another pattern. This might lead to endless loop by constructing nested autocommand carelessly.