How To Add A File Extension To vim Syntax Highlighting

Posted by Artem Russakovskii on April 2nd, 2008 in Databases, Linux, Programming

Updated: July 8th, 2009

Today I was asked a question about defining custom extensions for vim syntax highlighting such that, for example, vim would know that example.lmx is actually of type xml and apply xml syntax highlighting to it. I know vim already automatically does it not just based on extension but by looking for certain strings inside the text, like <?xml but what if my file doesn't have such strings?


After digging around I found the solution. Add the following to ~/.vimrc (the vim configuration file):

syntax on
filetype on
au BufNewFile,BufRead *.lmx set filetype=xml

After applying it, my .lmx file is highlighted:


Same principle works, for instance, for mysql dumps that I have to do from time to time. If they don't have a .sql extension, you'll get something like:



syntax on
filetype on
au BufNewFile,BufRead *.dump set filetype=sql

everything is fine:


But why and how does it work, you ask?

:help au :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}.
:help BufNewFile When starting to edit a file that doesn't exist.
:help BufRead When starting to edit a new buffer, after reading the file into the buffer.
:help filetype will actually tell this whole story in part B.

And that's how you do it, folks.

● ● ●
Artem Russakovskii is a San Francisco programmer and blogger. Follow Artem on Twitter (@ArtemR) or subscribe to the RSS feed.

In the meantime, if you found this article useful, feel free to buy me a cup of coffee below.

  • I used to hate VIM when I first started programming. Now I am powerless without it. It's amazing how feature-rich the text editor is. I still learn new VIM tricks 3-4 times a month.

  • Jimmy Janks

    This is the best ever, thanks for posting this!
    I would only add that you can spare yourself the "syntax on" and "filetype on" lines if these are already your defaults and just add the new to-be-highlighted extensions with the "au" line.

  • It was very helpful. Thanks!

  • Thanks for the tip, this helped me today 🙂

  • roger

    Thanks a lot !
    I was looking for this for a long time !


  • Shushan

    You made my day. Thanks!

  • In case this recipe doesn't works for anyone, just use this;
    :syntax on
    :set syn=php or whatever extension you want.

  • Merijn

    Thanks for the tip!

  • Amy

    You are awesome. Thanks for this!

  • Phani T

    Thanks a lot dude.
    i was looking for this tip from a long time.
    Its working just fine.

  • Vishal Kotcherlakota

    Running great on Vim on Slackware! Thanks for putting out this tip. It saved me a lot of digging through Vim's documentation. =)

  • chrish

    Awesome! Real time saver. Was preparing to RTFM 🙂

  • neurox

    Thanks – I needed this badly for Magento's .phtml files (which are actually PHP). Awesome! 🙂

  • Thanks.

  • Joel

    Thanks google, and thanks to you for the great tip. works like a champ.

  • Yo

    It may have been a while but it's still useful. Thanks!

  • John

    Just what I was looking for.

    Thanks dude!

  • Thanks! It's exactly what I needed.

  • Jake

    Hey I am trying to do this but it is not quite working as expected. It will highlight that file type BUT it also highlights other file types using that highlighting. (Bad).

    My problem is documented here if anyone has any input that would be much appreciated. (You don't need a username or password to reply).



    • Looks like you found the solution. SuperUser, StackOverflow, etc are great, aren't they?

  • Alexander

    Thx for the solution. I was needed to edit *.class files as php-scripts and you did a great help to me =)

  • Mohit

    Thanks for the tip. Just to add to this, the filetype should be all in small letters. I wanted to set the filetype to "Specman" (as it appears in filetypes list in the gvim menu), it didn't work untill I changed the filetype to "specman".

  • Justin

    Good one! You fixed my fugly phtml files.

  • Jie

    so cool artem! i searched on google and it gave me an answer. not that it did not happen before. but this time, the answer is from someone i know~

    • Haha, wouldn't be the first time this happens, but I love every time it does!

  • Matt Darby

    Still helping people! Thanks 😉

  • Jorge Medina


    I already knew how to use :setf, this is much better.

    Have a good day.

  • Harry Stamper

    Thank you, man.
    I hope you get to be millionaire.

  • Evelyn

    I had to edit a .ofx file today. Following your example i added this to my .gvimrc file

    augroup OFX
    au! BufNewFile,BufRead *ofx set filetype=xml
    augroup end

    Worked great!

  • John Murray

    This was very helpful! Thank you!

  • martin

    thanks for the hint.
    i love vim. it is a pain in the ass to get started but once you are in to it, you will never choose another text editor!
    best text editor for hackers.

    see ya folks

  • k00pa

    Thanks! Just what I needed 😛

  • Merker

    Perfect ! thanks

  • Snajperka89

    Years are passing and your tip is immortal 🙂 Thanks!

  • AnotherHappyUser

    Another Happy user for this tip.

    Thanks 🙂

  • kaewgb

    Thanks a lot! Really useful 🙂

  • Jason

    Thank you. I've been staring at a lot of black and white, and you just brought color to my world. 🙂

  • Scott

    Thanks for the tip. Now my .less files look like proper CSS.

  • Brooke

    Thanks! I was able to get Vim (on Mac Terminal.app) to recognize as Markdown files wth the extenson *.md. (Previously, it only recognized as Markdown files with extenstion *.markdown.)

    filetype on
    au BufNewFile,BufRead *.md set filetype=markdown

    Thanks again!

  • Adam Pippin

    Only issue I ran into was that I did not add "syntax on", as it was already in my .vimrc. Unfortunately, it was added as follows:

    if has('syntax') && (&t_Co > 2)
    syntax on

    The file type did not have a syntax (until I later defined one), and thus it was never enabled. I prefer my "syntax on" only in those conditions, so I forced it on for the extension in question by entering as:

    au BufNewFile,BufRead *.file syntax on
    au BufNewFile,BufRead *.file set filetype=html


  • ani

    thanks for the tip.
    works like a charm.

  • sckyo

    this is cool thanks for the tip

  • Yaniv

    Thank you. it helped me.

    if you need verilog, just put

    au BufNewFile,BufRead *.v_et set filetype=verilog

    on the GUI it is "Verilog HDL" which will not work on the command line

  • Suresh

    Many Thanks.

    This tip helped me a lot.

  • jmaasing

    Yeah, still helping people with this tip, thanks 🙂

  • sdhull

    Rock on! This is still helpful 🙂

  • Thank you so much Artem! Very useful!

  • Thanks. It was really useful.

  • huga


  • Dokinoki

    Thank you, it worked great with some custom php files with our own extension!

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