Time Machine utility, examine and manipulate Time Machine backups, restore data from backups, add or remove exclusions, and compare backups. Several, but not all, verbs require root privileges.

      tmutil verb [options]

     Throughout this manual, specific language is used to describe particular "realms" associated with Time
     Machine backups. It is important to understand this terminology to make effective use of tmutil and its

     backup source
             A volume currently being backed up by Time Machine.

     backup disk
             The HFS+ volume that contains Time Machine backups.

     backup destination
             In the case of a local destination, a synonym for backup disk. For network destinations, this
             is the AFP share on which the backup disk image resides.

     backup disk image (or backup image)
             A sparsebundle that, when mounted, is the backing store for a volume that is a backup disk.

     backup store
             The top-level "Backups.backupdb" directory at the root of a backup disk.

     machine directory
             A directory inside a backup store that contains all the backups for a particular computer. For
             local destinations, a backup store can contain multiple machine directories, all for separate

             A directory inside a machine directory that represents a single initial or incremental backup
             of one computer. The word "snapshot", in most contexts, is a generic term and is not to be confused
             with a "local Time Machine snapshot", which is a snapshot stored locally on the

     snapshot volume
             A directory inside a snapshot that represents a single initial or incremental backup of one
             backup source. E.g.,

             /Volumes/Chronoton/Backups.backupdb/thermopylae/2011-07-03-123456/Mac HD

     Each verb is listed with its description and individual arguments.

     help [verb]
             Print extended usage for a given verb. If no verb is provided, print a list of verbs and usage

             Turn on automatic backups. Requires root privileges.

             Turn off automatic backups. Requires root privileges.

             Turn on local Time Machine snapshots. Requires root privileges.

             Turn off local Time Machine snapshots and trigger automatic cleanup of accumulated local snapshot
             data. Requires root privileges.

             Create new local Time Machine snapshot.

     startbackup [-b | --block] [-r | --rotation] [-d | --destination dest_id]
             Perform a standard backup. This is equivalent to choosing "Back Up Now" from the Time Machine
             menu extra.

                 --block          Wait (block) until the backup is finished before exiting.
                 --rotation       Allow automatic destination rotation during the backup.
                 --destination    Perform the backup to the destination corresponding to the specified ID.

             Cancel a backup currently in progress.

     delete snapshot_path ...
             Delete one or more snapshots in an arbitrary machine directory. This verb can delete snapshots
             from backups that were not made by, or are not claimed by, the current machine. Requires root

     restore [-v] src ... dst
             Restore the item src, which is inside a snapshot, to the location dst. The dst argument mimics
             the destination path semantics of the cp tool. You may provide multiple source paths to
             restore. The last path argument must be a destination.

             When using the restore verb, tmutil behaves largely like Finder. Custom Time Machine metadata
             (extended security and other) will be removed from the restored data, and other metadata will
             be preserved.

             Root privileges are not strictly required to perform restores, but tmutil does no permissions
             preflighting to determine your ability to restore src or its descendants. Therefore, depending
             on what you're restoring, you may need root privileges to perform the restore, and you should
             know this ahead of time. This is the same behavior you would encounter with other copy tools
             such as cp or ditto. When restoring with tmutil as root, ownership of the restored items will
             match the state of the items in the backup.

     compare [-@esmugtdEX] [-D depth] [-I name] [snapshot_path | path1 path2]
             Perform a backup diff.

             If no arguments are provided, tmutil will compare the computer to the latest snapshot. If a
             snapshot path is provided as the sole argument, tmutil will compare the computer to the specified
             snapshot. If two path arguments are provided, tmutil will compare those two items to each
             other.  tmutil will attempt to inform you when you have asked it to do something that doesn't
             make sense or isn't supported.

             The compare verb allows you to specify what properties to compare. If you specify no property
             options, it is assumed that you want to compare a basic set of metadata. This default property
             set is equivalent to the -smugt option set. Specifying any property option overrides the
             default set.

                 -a    Compare all supported metadata.
                 -@    Compare extended attributes.
                 -e    Compare ACLs.
                 -s    Compare sizes.
                 -m    Compare file modes.
                 -u    Compare UIDs.
                 -g    Compare GIDs.
                 -t    Compare modification times.
                 -d    Compare file data forks.
                 -D    Limit traversal depth to depth levels from the beginning of iteration.
                 -E    Don't take exclusions into account when comparing items inside volumes.
                 -I    Ignore paths with a path component equal to name during iteration. This may be specified
                       multiple times.
                 -X    Print output in XML property list format.

     setdestination [-ap] arg
             Configure a local HFS+ volume or AFP share as a backup destination. Requires root privileges.

             When the -a option is provided, arg will be added to the list of destinations. Time Machine
             will automatically choose a backup destination from the list when performing backups. When the
             -a option is not provided, the current list of destinations will be replaced by arg.

             If you wish to set an HFS+ volume as the backup destination, arg should be the mount point of
             the volume in question. When setting an AFP destination arg takes the form:


             In the AFP case, the password component of the URL is optional; you may instead specify the -p
             option to enter the password at a non-echoing interactive prompt. This is of particular interest
             to the security-conscious, as all arguments provided to a program are visible by all users
             on the system via the ps tool.

     destinationinfo [-X]
             Print information about destinations currently configured for use with Time Machine. For each
             backup destination, the following information may be displayed:

                 Name          The volume label as shown in Finder.
                 Kind          Whether the destination is locally attached storage or a network device.
                 URL           In the case of a network destination, the URL used for Time Machine configuration.
                 Mount Point   If the volume is currently mounted, the path in the file system at which it
                               was mounted.
                 ID            The unique identifier for the destination.

             When more than one destination is configured, the most recent backup destination will be marked
             with the > indicator.

             When the -X option is provided, output will be printed in XML property list format.

     removedestination identifier
             Remove the destination with the specified unique identifier from the Time Machine configuration.
             Requires root privileges.

             To obtain the unique identifier for a destination, see destinationinfo.

     addexclusion [-p] item ...
             Configure an exclusion that tells Time Machine not to back up a file, directory, or volume during
             future backups.

             There are two kinds of user-configurable exclusions in Time Machine. The first, which is the
             default behavior for the addexclusion verb, is a location-independent ("sticky") exclusion that
             follows a file or directory. When the file or directory is moved, the exclusion goes with the
             item to the new location. Additionally, when the item is copied, the copy retains the exclusion.

             The second kind of exclusion is what is known as a fixed-path exclusion. In this scenario, you
             tell Time Machine that you want a specific path to be excluded, agnostic of the item at that
             path. If there is no file or directory at the specified path, the exclusion has no effect; if
             the item previously at the path has been moved or renamed, the item is not excluded, because it
             does not currently reside at the excluded path. As a consequence of these semantics, moving a
             file or directory to the path will cause the item to be excluded--fixed-path exclusions are not
             automatically cleaned up when items are moved or deleted and will take effect again once an
             item exists at an excluded path.

             The -p option sets a fixed-path exclusion as described above. Requires root privileges.

             Volume exclusions can be set with the addexclusion verb. The -p option is ignored for volumes;
             exclusions set on volumes track the volume regardless of volume name or mount path changes.
             Erasing the volume will cause it to be included in future backups. (See associatedisk.)
             Requires root privileges.

     removeexclusion [-p] item ...
             Configure Time Machine to back up a file, directory, or volume during future backups. This verb
             follows the same usage, exclusion style, and privilege semantics as addexclusion.

     isexcluded [-X] item ...
             Determine if a file, directory, or volume are excluded from Time Machine backups.

             When the -X option is provided, output will be printed in XML property list format.

             # example output for an excluded item
             thermopylae:~ thoth$ tmutil isexcluded /Users/admin/Desktop/foo.txt
             [Excluded]      /Users/admin/Desktop/foo.txt

             # example output for an item that is not excluded
             thermopylae:~ thoth$ tmutil isexcluded /Users/admin/Desktop/bar.txt
             [Included]      /Users/admin/Desktop/bar.txt

     inheritbackup {machine_directory | sparsebundle}
             Claim a machine directory or sparsebundle for use by the current machine. Requires root privileges.

             Machine directories and sparsebundles are owned by one computer at a time, and are tracked by
             unique identifiers rather than computer name, host name, or ethernet address. The inheritbackup
             verb reassigns the identity of the specified item, reconfiguring it so the current host recognizes
             it during backups. When inheriting a sparsebundle, the machine directory within will also
             be claimed.

             Inheriting is typically only one step in the process of configuring a backup for use by a
             machine. You may also need to use setdestination, associatedisk, or both, depending on the situation.

             One machine can own multiple machine directories and sparsebundles, but it is ill-advised for
             them to reside in the same place. In such a situation, which will be chosen during a backup is
             undefined. As a result, inheritbackup will attempt to detect possible identity collisions
             before making changes.

     associatedisk [-a] mount_point snapshot_volume
             Bind a snapshot volume directory to the specified local disk, thereby reconfiguring the backup
             history. Requires root privileges.

             In macOS, HFS+ volumes have a persistent UUID that is assigned when the file system is created.
             Time Machine uses this identifier to make an association between a source volume and a
             snapshot volume. Erasing the source volume creates a new file system on the disk, and the previous
              UUID is not retained. The new UUID causes the source volume -> snapshot volume assocation
             to be broken. If one were just erasing the volume and starting over, it would likely be of no
             real consequence, and the new UUID would not be a concern; when erasing a volume in order to
             clone another volume to it, recreating the association may be desired.

             A concrete example of when and how you would use associatedisk:

             After having problems with a volume, you decide to erase it and manually restore its contents
             from a Time Machine backup or copy of another nature. (I.e., not via the macOS installer's
             System Restore feature or Migration Assistant.) On your next incremental backup, the data will
             be copied anew, as though none of it had been backed up before. Technically, it is true that
             the data has not been backed up, given the new UUID. However, this is probably not what you
             want Time Machine to do. You would then use associatedisk to reconfigure the backup so it
             appears that this volume has been backed up previously:

             Mac64:~ thoth$ sudo tmutil associatedisk [-a] "/Volumes/MyNewStuffDisk"  "/Volumes/Chronoton/Backups.backupdb/Mac64/Latest/MyStuff"

             The result of the above command would associate the snapshot volume MyStuff in the specified
             snapshot with the source volume MyNewStuffDisk. The snapshot volume would also be renamed to
             match. The -a option tells associatedisk to find all snapshot volumes in the same machine
             directory that match the identity of MyStuff, and then perform the association on all of them.

             Print the path to the most recent snapshot for this computer.

             Print paths for all of this computer's completed snapshots.

             Print the path to the current machine directory for this computer.

     calculatedrift machine_directory
             Analyze the snapshots in a machine directory and determine the amount of change between each.
             Averages are printed after all snapshots have been analyzed. This may require root privileges,
             depending on the contents of the machine directory.

     uniquesize path ...
             Analyze the specified path and determine its unique size. The figure reported by uniquesize
             represents things that only exist in the specified path; things that are hard-linked in other
             places are not tallied.

     In most situations, tmutil exits 0 on success, >0 otherwise.

If tmutil returns 0B, it may need to be granted access to 'private application data' on the backup disk.

Grant this to your terminal application in
System Preferences ➞ Security & Privacy ➞ Privacy ➞ Full Disk Access.


Add a directory or volume to the exclusion list:

$ tmutil addexclusion /ss64docs

Remove a directory or volume from the exclusion list:

$ tmutil removeexclusion /ss64docs

Manually run the backup:

$ tmutil startbackup

Compare the March 27 2024 10:11:00am and March 26 18:45:21pm snapshots of a computer named "Shenelu's Mac", on a backup volume named "Backup Disk", the two paths given must already exist on the backup disk:

$ cd "/Volumes/Backup Disk/Backups.backupdb/Shenelu's Mac"
tmutil compare 2024-03-27-101100 2024-03-26-184521

“The past is always tense, the future perfect” ~ Zadie Smith

Related macOS commands

rsync - Remote file copy - Sync file tree.
rsnapshot - Save multiple backups with rsync.

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