Nvim: Autocommand Examples, Nesting, and Pattern Matching

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 don'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. For example, 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. If you want to skip autocommands for one command, use the |:noautocmd| command modifier or the 'eventignore' option. 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

This section provides examples of autocommands for reading and writing compressed files using gzip, including how to use `:autocmd!` to avoid duplicate autocommands. It explains how autocommands interact with the changed flag and offers tips for executing Normal mode commands and managing the 'modified' option. The section further discusses autocommand nesting using the `++nested` flag and how to skip autocommands using `:noautocmd` or the 'eventignore' option. It also covers how Vim handles missing <EOL> characters when reading and writing files. Finally, the section presents how to specify multiple patterns for autocommands using commas.