Question

I have some (log4j generated) logfiles to go through; I know their format pretty well (I mean I have already got off-the-peg regexes etc I can use).

I want to automatically highlight them in VIM when I load them up (*.log).

A logfile entry looks something like this:

YYYY-MM-DD HH:MM:ss,SSS [...] #LOG-LEVEL# [...] Message

Where #LOG-LEVEL# is one of the standard ‘ERROR’, ‘INFO’, ‘DEBUG’, ‘FATAL’….and the ‘YYYY-MM…’ represents the date/time to millisecond resolution.

To get me started , what are the steps needed to get the date-string highlighted in (say) yellow-background with blue text – and also when the text reads ‘ ERROR ‘ this should have a red-background with white text.

I have tried going through some tutorials on this, but can’t find one which is simple enough to understand, so I’m after some real basic steps here !

Cheers

EDIT:
Here’s the summary of what I did, based on the instructions below:

1. Created the syntax file ‘log.vim’ in .vim\syntax (see below for example content).

2. Created a file in .vim\ftdetect\log.vim with the following content:

   au BufRead,BufNewFile *.log set filetype=log

3. Made sure the following are in my startup settings:

   syntax on
   filetype on

Answer 1

There are three ways of defining syntax items (see :help :syn-define):

• Keywords: these are for items that are simple strings of keyword characters. This is the fastest matcher.
• Matches: these are regular expressions for matching.
• Regions: these are for long regions that are likely to contain other items.

There are various arguments that make things more complicated (to do with matches within regions etc), see :help :syn-arguments for a discussion of this.

There is a priority that comes into effect (see :help :syn-priority).

Colouring is controlled by the highlight command and is separate to the syntax commands.

A simple way to get started would be to use a match to detect the date and a keyword to detect error. Then use highlight to make the colours come to life:

" This creates a keyword ERROR and puts it in the highlight group called logError
:syn keyword logError ERROR
" This creates a match on the date and puts in the highlight group called logDate.  The
" nextgroup and skipwhite makes vim look for logTime after the match
:syn match logDate /^\d\{4}-\d\{2}-\d\{2}/ nextgroup=logTime skipwhite

" This creates a match on the time (but only if it follows the date)
:syn match logTime /\d\{2}:\d\{2}:\d\{2},\d\{3}/

" Now make them appear:
" Link just links logError to the colouring for error
hi link logError Error
" Def means default colour - colourschemes can override
hi def logDate guibg=yellow guifg=blue
hi def logTime guibg=green guifg=white

Bung all of that in ~/.vim/syntax/log.vim and make sure the file type is set properly (see :help filetype.txt) – it should then load automatically.

Hopefully that should give you something to get going with. Have a (very gradual) read of the various sections of :help syntax.txt and :help usr_44.txt for further info.