Prior to Yosemite Notification Center settings stored in an sqlite db in ~/Library/Application\ Support/NotificationCenter/ Now this folder does not exist anymore, where does the OS store those settings?
The database has moved on Yosemite. The following command takes to you to its new location:
cd `getconf DARWIN_USER_DIR`/com.apple.notificationcenter/db
Because I was looking for the file that notifications are stored in I came to this page (using macOS 10.13.6 High Sierra).
Here are some facts:
getconf command … with the DeviceVariable and DeviceName parameters, [returns] the value of the disk device name or location, for the device path specified by the DeviceName parameter
The above code returns (with "cd" omitted!):
/var/folders/_d/pg2g__g17nzfwrv64j8ddvn80000gn/0//com.apple.notificationcenter/db: is a directory
Inside this/my folder I found:
db db-shm db-wal db2upgraded
When some action takes place (I sent a notification) only
db-wal gets updated immediately. So notifications are "registered" there somehow; interestingly, recurring ones are listed several times, meaning, a kind of "history" could be created once the db code is "translated".