macOS TimeMachine cheatsheet

macOS_timemachine_cheatsheet.txt

# the man page for tmutil
man tmutil

# calculate drift on backups (cpu / io intensive)
tmutil calculatedrift backup_folder

# list backups
tmutil listbackups

# set backup destination 
tmutil setdestination <volume_name>

# remove backup destination 
tmutil removedestination [volume_name]

# information on destination volumes configured
tmutil destinationinfo

# exclude directory 
tmutil addexclusion "<path_to_exclude>"

# check if some path / file is excluded
tmutil isexcluded "<path_to_check>"

# list local snapshots (by volume) and date
tmutil listlocalsnapshots /
tmutil listlocalsnapshotdates /

# delete local snapshots (by volume and date)
tmutil deletelocalsnapshots date

# thin the snapshots for a mount point
tmutil thinlocalsnapshots mount_point [purge_amount]
    # when purge_amount is specified, tmutil will attempt to reclaim purge_amount 
    # in bytes by thinning snapshots.



# local backups on / off-  depends on system version
sudo tmutil enablelocal
sudo tmutil disablelocal

# stop start backups
tmutil stopbackup
tmutil startbackup

# time machine on or off
sudo tmutil enable
sudo tmutil disable

delete backups (one by one)
tmutil delete /Volumes/drive_name/Backups.backupdb/mac_name/YYYY-MM-DD-hhmmss

delete all snapshots (warning danger will robbinson)
for delsnap in $(tmutil listlocalsnapshotdates | grep "-") ; do sudo tmutil deletelocalsnapshots $delsnap ; done

# find the machine's backup direcoty
sudo tmutil machinedirectory

# compact a sparce time machine backup (if it is on a network volume)
hdiutil compact /Volumes/TimeMachineMountPoint/YourBackupName.sparsebundle

# limiting the size of timemachine backup
# from : https://www.defaults-write.com/time-machine-setup-a-size-limit-for-backup-volumes/

sudo defaults write /Library/Preferences/com.apple.TimeMachine MaxSize -integer XX
Replace XX by the number of megabytes that you want to use, 1 GB = 1024 MB

Example 200GB:
sudo defaults write /Library/Preferences/com.apple.TimeMachine MaxSize -integer 204800

To remove the limit:
sudo defaults delete /Library/Preferences/com.apple.TimeMachine MaxSize

# alterative (best) approach is to partition your volume up into a dedicated time machine backup volume

# start backup after setting limits
tmutil startbackup --auto --rotation

# start backup options from man page 
#    --auto           Run the backup in a mode similar to system-scheduled backups.
#    --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.

# if you are dealing with snapshots on a local volume, then the bottom of the man page will 
# provide lots of options fo deleting and thining local snapshots.

timemachine_delete_old_backups.bash

#!/bin/bash
# This script will automatically find the oldest TM backup for your computer, 
# tell you which is the oldest and newest backup and provide you with a prompt to 
# delete the oldest backup. You must enter Y and enter your administrator password 
# to delete it. Stolen from StackExchange (thanks nohillside) : 
# https://apple.stackexchange.com/questions/39287/how-can-i-manually-delete-old-backups-to-free-space-for-time-machine

#
# potentially helpful for pruning (less work) : https://github.com/oPromessa/tm_del_old_baks
#

COMPUTER_NAME=$(scutil --get ComputerName)
NBACKUPS=$(tmutil listbackups | grep "$COMPUTER_NAME" | wc -l)
OLDEST_BACKUP=$(tmutil listbackups | grep "$COMPUTER_NAME" | head -n1)
LATEST_BACKUP=$(tmutil latestbackup)
echo Latest backup: $LATEST_BACKUP

if [[ -n "$LATEST_BACKUP" && "$LATEST_BACKUP" != "$OLDEST_BACKUP" ]]; then
     echo -n "$NBACKUPS backups. Delete oldest: ${OLDEST_BACKUP##*/} [y/N]? "
     read answer
     case $answer in
         y*)
             echo Running: sudo tmutil delete "$OLDEST_BACKUP"
             sudo time tmutil delete "$OLDEST_BACKUP"
             ;;
         *)
             echo No change
             ;;
     esac
 else
     echo "No backup available for deletion"
 fi