lsregister: How Files Are Handled in Mac OS X

The lsregister command is used to query and manage the Launch Services database, or the database that is used to determine the default application used to open files of various types. lsregister is part of Core Services, and stored in /System/Library/Frameworks/CoreServices.framework/Versions/A/Frameworks/LaunchServices.framework/Versions/A/Support. To see the options available to lsregister, run the command with no operators:

/System/Library/Frameworks/CoreServices.framework/Versions/A/Frameworks/LaunchServices.framework/Versions/A/Support/lsregister

You can dump the database to the screen using the -dump option:

/System/Library/Frameworks/CoreServices.framework/Versions/A/Frameworks/LaunchServices.framework/Versions/A/Support/lsregister -dump

You can then grep the database or redirect the output into a text file for parsing:

/System/Library/Frameworks/CoreServices.framework/Versions/A/Frameworks/LaunchServices.framework/Versions/A/Support/lsregister -dump > dump.txt

Sometimes applications don’t open with a given file type. When this happens, you can quickly and easily check if the problem has to do with the launchservices database. To do so run the open command and define the application (using the -a option) followed by the app and then the file. For example, to open an XML file called daneel.xml in TextWrangler (assuming your working directory contains bob.xml):

open -a TextWrangler.app bob.xml

You can force an application to re-register file types for that application using the -f option followed by the application path. For example, to re-register Xcode:

/System/Library/Frameworks/CoreServices.framework/Versions/A/Frameworks/LaunchServices.framework/Versions/A/Support/lsregister -f /Developer/Applications/Xcode.app

You can also unregister a specific application using the -u option. To unregister Xcode you would use the -u option:

/System/Library/Frameworks/CoreServices.framework/Versions/A/Frameworks/LaunchServices.framework/Versions/A/Support/lsregister -u /Developer/Applications/Xcode.app

The lsregister command is actually just a front-end management tool for the ~/Library/Preferences/com.apple.LaunchServices.plist file. The file’s contents can be read (in an unparsed form) using defaults:

defaults read ~/Library/Preferences/com.apple.LaunchServices

The launchservices database is also responsible for determining whether a file type is quarantined by default (and those files that are quarantined throw a message to users when opened for the first time). To disable such a feature:

defaults write com.apple.LaunchServices LSQuarantine -bool NO

The database can become pretty large and unwieldy. There are applications registered in the local domain, system domain and each user’s domain. You can always clear these out using the following command, which also recursively rebuilds based on the output of a -lint option:

/System/Library/Frameworks/CoreServices.framework/Versions/A/Frameworks/LaunchServices.framework/Versions/A/Support/lsregister -kill -r -domain local -domain system -domain user

To check the progress:

/System/Library/Frameworks/CoreServices.framework/Versions/A/Frameworks/LaunchServices.framework/Versions/A/Support/lsregister -v

To set a specific application to open a file type, use the application’s domain out of the -dump output in an LSHandlerRoleAll and the file extension in an LSHandlerContentType in the LSHandlers array of com.apple.LaunchServices, as follows (to change txt for Text Edit – aka com.apple.textedit):

defaults write com.apple.LaunchServices LSHandlers -array '{ LSHandlerContentType = "txt"; LSHandlerRoleAll = "com.apple.textedit"; }';

You can also set the default application for a network protocol (e.g. smb://, rdp://, vnc://, http:// and https://). Because the options for lsregister leave one wanting in some ways (the commands to set file types to a specific application are a bit overly complicated one could argue), there is an awesome front end app from Andrew Mortensen, aptly called duti, available at http://duti.sourceforge.net/index.php. With duti installed, the command to set the default browser for http would be:

/usr/local/bin/duti -s com.apple.safari http

Note: When working with lsregister, one should first clear the state for that application: http://krypted.com/mac-os-x/controlling-saved-application-states.

Finally, there’s a lot that Launch Services does and is involved in. For more information on LaunchServices, check out the Apple developer library information here.

4 Comments

  • Patrick Fergus
    January 9, 2012 - 6:25 am | Permalink

    Thought duti was written by Andrew Mortensen?

    http://duti.sourceforge.net/license.php

  • July 6, 2012 - 8:21 am | Permalink

    Great article!

    Do you know how to get lsregister to apply to all old and new users in OS X Lion? When I run the command it only works for the user context I run the command with. When I log onto a new or old user account and run the lsregister -dump command I can’t see the application I added with an the previous user account

    The command I run is like this.

    /System/Library/Frameworks/CoreServices.framework/Frameworks/LaunchServices.framework/Support/lsregister -R -f -v

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  • schiroko
    August 6, 2012 - 9:16 am | Permalink

    “open -a TextWrangler.app bob.xml”

    there is the filename, daneel.xml?

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