A commandline script for MacOS, to create a TimeMachine Backup Volume on a non-Apple formatted disk

tmMakeImage

#!/bin/bash
# 2015 Updates to sunkid's script. chrisfcarroll
# - added more quote marks to cope with e.g. spaces in volume names.
# - get machine UUID from ioreg instead of parsing and system report.
# - added steps to tell Time Machine to use your new backup drive.
# - renamed. 
# Make it executable with e.g. chmod a+x tmMakeImage && mv tmMakeImage /usr/local/bin.
#
# A bash script to create a time machine disk image suitable for
# backups with OS X 10.6 (Snow Leopard) and later.
# This script probably only works for me (and me!), so try it at your own peril!
# Use, distribute, and modify as you see fit but leave this header intact.
# (R) sunkid - September 5, 2009
# 
# This will create a time machine ready disk image named with your 
# computer's name with a maximum size of 600GB and copy it to 
# /Volumes/backup. The image "file" (it's a directory, really) will 
# contain the property list file that SL's TM needs.
# 
# . ./tmMakeImage 600GB /Volumes/backup
#
# Based on a script found here : 
# http://www.insanelymac.com/forum/index.php?showtopic=184462

usage ()
{
     echo ${errmsg}
     echo ""
     echo "tmMakeImage"
     echo
     echo " usage: tmMakeImage size [directory] [GO]"
     echo " Create a sparsebundle disk image with a max storage size of <size>" 
     echo " (defaults to GB but you can specify MB)"
     echo " and copy it to your backup volume (if specified)."
     echo
     echo  The GO parameter requires sudo. 
     echo  It will mount the new image and tell Time Machine to use it for backups.
     echo
}

# test if we have two arguments on the command line
if [ $# -lt 1 ]
then
    usage
    exit
fi

# see if there are two arguments and we can write to the directory
if [ $# -gt 1 ]
then
  if [ ! -d "$2" ]
  then
    errmsg=${2}": No such directory"
      usage
      exit
  fi
  if [ ! -w "$2" ]
  then
    errmsg="Cannot write to "${2}
    usage
      exit
  fi
fi

SIZE=$1
DIR=$2
NAME=`scutil --get ComputerName`;
UUID=`ioreg -rd1 -c IOPlatformExpertDevice | awk '/IOPlatformUUID/ { split($0, line, "\""); printf("%s\n", line[4]); }'`

# get busy
echo -n "Generating disk image ${NAME}.sparsebundle with size ${SIZE} ... "
hdiutil create -size ${SIZE}G -fs HFS+J -type SPARSEBUNDLE \
  -volname 'Time Machine Backups' "${NAME}.sparsebundle" >> /dev/null 2>&1

echo "done!"

echo -n "Generating property list file with uuid $UUID ... "

PLIST=$(cat <<EOFPLIST
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
        <key>com.apple.backupd.HostUUID</key>
        <string>$UUID</string>
</dict>
</plist>
EOFPLIST)

echo $PLIST > "${NAME}.sparsebundle"/com.apple.TimeMachine.MachineID.plist
echo "done!"

if [ $# -gt 1 ]
then
  echo "Copying ${NAME}.sparsebundle to $DIR ... "
  cp -pfr "${NAME}.sparsebundle" "$DIR/${NAME}.sparsebundle"
fi

if [ $# -gt 2 ]
then
  echo Using new image for backups ...
  echo
  sudo hdiutil attach "$DIR/${NAME}.sparsebundle"
  #The above line needs root to turn off "ignore ownership permissions" I think. An alternative might
  #be sudo vsdbutil -a "/Volumes/Time Machine Backups"
  #
  sudo tmutil setdestination "/Volumes/Time Machine Backups"
  echo
  echo Done. To start backups immediately:
  echo
  echo   tmutil startbackup
  echo
else
  echo "Finished! Happy backups!"
  echo
  echo Next Steps.
  echo
  echo Mount the new backup drive by double-clicking in the finder.
  echo 
  echo It might be that if you then leave it and wait an hour, Time Machine will pick it up.
  echo 
  echo Other options:
  echo
  echo From the command line:
  echo sudo mkdir /Volumes/Time\ Machine\ Backups/Backups.backupdb
  echo sudo tmutil setdestination /Volumes/Time\ Machine\ Backups/
  echo [optional tmutil startbackup]
  echo
  echo Or, you can try copying existing backups onto your new disk image:
  echo https://support.apple.com/en-us/HT202380
fi