MacOS – Editing System Preferences via Terminal

command linemacosterminalunix

Am looking to edit system preferences settings via the command line but cannot for the life of me find the correct names of variables.

In Login Options under Users & Groups, I would like to be able to change the Display login window from list of users to 'name and password'.
In Date & Time, I would like to know how I change the time to a server we use.
Enable fields in Sharing
Setup Energy Saver settings

It would be great if someone can help me out or point me in the right direction as I know you edit the preferences .plists but its knowing what to add or finding the preferred naming conventions.

Thanks.

Best Answer

First off, you can check out a website that lists a lot of these things: http://secrets.blacktree.com/

I, however, just took a brute-force solution:

Copy the Preferences folder

$ cp -r /Library/Preferences before

Launch System Preferences. Make a change via the GUI. Probably best to do one change at a time, e.g. I changed "Display Login Window as:" from "List of users" to "Name and password". Quit System Preferences.

Copy the Preferences folder again:

$ cp -r /Library/Preferences after

See which files changed:

$ diff -ur before after
Binary files before/Preferences/com.apple.loginwindow.plist and after/Preferences/com.apple.loginwindow.plist differ

Compare the two versions. Since they are binary files, you'll need to convert them to XML for comparison. I use an alias for this:

$ alias plist='plutil -convert xml1 -o /dev/stdout'
$ diff -u <(plist before/Preferences/com.apple.loginwindow.plist) <(plist after/Preferences/com.apple.loginwindow.plist)
--- /dev/fd/63  2013-01-23 18:20:29.000000000 +0200
+++ /dev/fd/62  2013-01-23 18:20:29.000000000 +0200
@@ -9,7 +9,7 @@
    <key>RetriesUntilHint</key>
    <integer>3</integer>
    <key>SHOWFULLNAME</key>
-   <false/>
+   <true/>
    <key>lastUser</key>
    <string>loggedIn</string>
    <key>lastUserName</key>

At this point we have located the setting. Confirm we have it with defaults:

$ defaults read /Library/Preferences/com.apple.loginwindow SHOWFULLNAME
1
$ sudo defaults write /Library/Preferences/com.apple.loginwindow SHOWFULLNAME -bool false
$ defaults read /Library/Preferences/com.apple.loginwindow SHOWFULLNAME
0

Launch System Preferences and confirm it changed.

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