tl;dr sudo/usr/libexec/PlistBuddy-c'set:LaunchEvents:com.apple.time:"BackupInterval":Interval86400'/System/Library/LaunchDaemons/com.apple.backupd-auto.plist

method 1 : vim (or any editor)

  • open the file for edition

    sudo vim /System/Library/LaunchDaemons/com.apple.backupd-auto.plist
    
  • replace 36000 (one hour) by 86400 (one day), then quit:

    :%s/3600/86400/g
    :wq!
    

method 2 : plistbuddy

  • you can make it in one line:

    sudo /usr/libexec/PlistBuddy -c 'set  :LaunchEvents:com.apple.time:"Backup Interval":Interval 86400' /System/Library/LaunchDaemons/com.apple.backupd-auto.plist
    
  • this method use the PlistBuddy method to read / write the file. this utility can be used interactively

    sudo /usr/libexec/PlistBuddy  /System/Library/LaunchDaemons/com.apple.backupd-auto.plist
    
  • but also directly:

    sudo /usr/libexec/PlistBuddy -c 'print  ' /System/Library/LaunchDaemons/com.apple.backupd-auto.plist
    sudo /usr/libexec/PlistBuddy -c 'print  :LaunchEvents:com.apple.time ' /System/Library/LaunchDaemons/com.apple.backupd-auto.plist
    sudo /usr/libexec/PlistBuddy -c 'print  :LaunchEvents:com.apple.time:"Backup Interval" ' /System/Library/LaunchDaemons/com.apple.backupd-auto.plist
    sudo /usr/libexec/PlistBuddy -c 'print  :LaunchEvents:com.apple.time:"Backup Interval":Interval ' /System/Library/LaunchDaemons/com.apple.backupd-auto.plist
    sudo /usr/libexec/PlistBuddy -c 'set  :LaunchEvents:com.apple.time:"Backup Interval":Interval 3600' /System/Library/LaunchDaemons/com.apple.backupd-auto.plist
    

finally

  • reboot.