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.
Syntax
tmutil verb [options]
BACKUP STRUCTURE
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
manual.
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
computers.
snapshot
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
computer.
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
VERBS
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
summaries.
enable
Turn on automatic backups. Requires root privileges.
disable
Turn off automatic backups. Requires root privileges.
enablelocal
Turn on local Time Machine snapshots. Requires root privileges.
disablelocal
Turn off local Time Machine snapshots and trigger automatic cleanup of accumulated local snapshot
data. Requires root privileges.
snapshot
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.
Options:
--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.
stopbackup
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
privileges.
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.
Options:
-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:
afp://user[:pass]@host/share
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.
latestbackup
Print the path to the most recent snapshot for this computer.
listbackups
Print paths for all of this computer’s completed snapshots.
machinedirectory
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.
EXIT STATUS
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
rsync - Remote file copy - Sync file tree.
rsnapshot - Save multiple backups with rsync.