Moving Dictionary.app

Friday, 2. 05. 2008  –  Category: all, sw

OS X does a good job of tracking what applications are where and what they do. I have little idea how this works, but if I move VLC.app into a new home then all the files that open in VLC still work. Great. I imagine it involves FSEvents and gobs of XML somewhere.

However the magic doesn’t touch everything. I was so bold as to move Dictionary.app from its default home in /Applications into the Utilities subdirectory. This broke the Ctrl-Cmd-D system-wide (Cocoa-wide?) lookup box. I don’t use it that much but that irked me nonetheless.

Console logs included this:

com.apple.launchd[335] (com.apple.DictionaryPanelAgent[490]): posix_spawn("/Applications/Dictionary.app/Contents/SharedSupport/DictionaryPanel.app/Contents/MacOS/DictionaryPanel", ...): No such file or directory

Clearly something thinks it knows where the nested DictionaryPanel application should live. This thing is a launchd-managed process used by the keyboard shortcut, configured out of /System/Library/LaunchAgents/com.apple.DictionaryPanelAgent.plist.

The hoojah to tweak this does of course involve XML:


$ launchctl unload /System/Library/LaunchAgents/com.apple.DictionaryPanelAgent.plist

$ plutil -convert xml1 -o - /System/Library/LaunchAgents/com.apple.DictionaryPanelAgent.plist | perl -pe 's|/Applications/Dictionary.app/|/Applications/Utilities/Dictionary.app/|;' > /var/tmp/com.apple.DictionaryPanelAgent.plist

$ plutil -lint /var/tmp/com.apple.DictionaryPanelAgent.plist
/var/tmp/com.apple.DictionaryPanelAgent.plist: OK


$ plutil -convert binary1 /var/tmp/com.apple.DictionaryPanelAgent.plist

$ mkdir /Library/LaunchAgents-orig

$ sudo mv /System/Library/LaunchAgents/com.apple.DictionaryPanelAgent.plist /Library/LaunchAgents-orig && sudo cp /var/tmp/com.apple.DictionaryPanelAgent.plist /System/Library/LaunchAgents/com.apple.DictionaryPanelAgent.plist

$ launchctl load /System/Library/LaunchAgents/com.apple.DictionaryPanelAgent.plist

The last step was intended to make the change work this session, but it didn’t work. The DictionaryPanelAgent still loads but didn’t do anything until logged out and in again. I think this is something to do with launchctl domains / sessiontype. Blunder factor is high.

This violates the “don’t frig with stuff in /System” principle but I don’t know how else to solve it. The modified plist could go in /Library/LaunchAgents of course, but I’d still need to disable the system version (with launchctl unload -w) which is equally naughty. I think.

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