Command Line Interface

For help using the weresync command when you are on the command line, use the help flag on the weresync command:

$ weresync -h

Basic Usage



The WereSync daemon requires root permissions to run, because it has to access block devices. Standard linux permissions restrict access to block devices to ordinary users.

WereSync will copy GPT, MBR, and LVM drives. The source drive must have a valid disk label (such a disk label can be created with the gdisk or fdisk command). All dependencies must be installed.


First start the weresync-daemon as root. Usually you want it to run in the background:

$ sudo weresync-daemon > /dev/null 2>&1 &

WereSync always requires a source drive and a target drive. The source drive comes first. So to copy from /dev/sda to /dev/sdb, use this command:

$ weresync /dev/sda /dev/sdb

This will simply copy data from one partition to the another, and if the partitions are different, you will encounter an error. To have WereSync fix your target drives partitions, use the -C flag:

$ weresync -C /dev/sda /dev/sdb

On subsequent backups, you may not want to include the -C flag, since this can sometimes trigger unnecessary repartitioning.


WereSync supports the copying of LVM drives with the -l flag:

$ weresync -C -l -B 1 volume-group /dev/sda /dev/sdb

It is highly recommended to pass which partition of the drive your boot partition is stored on, if you have a boot partition seperate from the VG. If you have your /boot folder inside the VG, your bootloader installation mileage may vary.

Bootloader Installation

WereSync will attempt to update the target drive’s system to it will boot up properly. By default this simply changes the UUIDs in the files of the /boot folder and EFI system partition, but specific bootloader installation plugins can also be specified.

For this to work, it is highly recommended that you pass the root partition with the -g flag:

$ weresync -g 1 /dev/sda /dev/sdb

If this is not passed, WereSync will attempt to discover the root filesystem on its own, but this is unreliable.

In order for a drive on an EFI system to be made bootable, the partition number of the EFI system partition to be passed to WereSync with the -E flag. In this case, the root filesystem should be installed on (-g flag) should also be passed, especially if the efi partition comes before the grub partition on the partition list, as the efi partition can trigger the mechanisms used to find the grub partition.

$ weresync -E 2 -g 3 /dev/sda /dev/sdb

If you have your boot folder on a seperate partition, be sure to let WereSync know which partition that folder is on with the -B flag:

$ weresync -E 1 -g 2 -B 3 /dev/sda /dev/sdb

Obviously replace the numbers with the proper values for your system.

Bootloader Plugins

Some bootloaders, especially those for MBR booting, require a more specific process. Bootloader plugins allow such a process to occur. All plugins available will be displayed at the end of the help message displayed with the -h flag. The specific plugin to use may be passed with the -L flag:

$ weresync -L grub2 -E 1 -g 2 /dev/sda /dev/sdb

For more information on installing and creating bootloader plugins see the bootloader plugin page

Image Files

WereSync supports image files normally. If either the target or the source ends in “.img” WereSync will automatically consider it an image file and mount it as such. Currently there is no way to mark files not ending in .img as image files.

To create an image file on linux, use:

$ dd if=/dev/zero of=my_image.img bs=1M count=<size in MB>
$ sgdisk my_image.img -o

The second command creates a partition table on the command, which is currently needed by WereSync to start analyzing a drive.

In-Depth Parameter Definitions


weresync [-h] [-C] [-s SOURCE_MASK] [-t TARGET_MASK]
           [-M TARGET_MOUNT] [-r RSYNC_ARGS] [-l] [-L BOOTLOADER]
           [-v] [-d] source target

Long Option

Short Option





Displays the help message




Checks if all partitions are large enough and formatted correctly to allow drive to be copied. If the partitions are not valid, the target drive will be re-partitioned and reformatted.

If unset, no checking occurs.

–source-mask MASK


A string to be passed to format() that will produce a partition identifier (/dev/sda1 or such) of the source drive when passed two arguments: the identifier (“/dev/sda”) and a partition number in that order.


–target-mask MASK


Same as –source-mask, but applied to the target drive.


–excluded-partitions LIST


A list of comma separated partition numbers that should not be searched or copied at any time. These partitions will still be formatted if -C is passed.




If passed the program will halt if there are any errors copying. This flag is not recommended because it will halt even if encountering a normal issue, like a swap partition.


–root-partition PART_NUM


The partition mounted on /. It is recommended to pass this always, but WereSync will attempt to find the main partition even if it is not passed.

None, WereSync searches for the partition.

–boot-partition PART_NUM


The partition that should be mounted on /boot of the grub_partition. If you have a separate boot partition, you must use this flag.

None, no partition mounted.

–efi-partition PART_NUM


The partition that should be mounted on /boot/efi of the grub_partition. If passed this will create the /boot/efi folder if it does not exist and pass it to grub. Required if you have an EFI partition.


–source-mount DIR

-m DIR

The directory to mount partitions from the source drive on. Cannot be the same as –target-mount.

None, randomly generated directory in the /tmp folder.

–target-mount DIR


The directory to mount partitions from the target drive on. Cannot be the same as –source-mount.

None, randomly generated directory in the /tmp folder.

–rsync-args RSYNC_ARGS


The arguments to be passed to the rsync instance used to copy files.

-aAXxvH –delete



This argument expects either one or two arguments specifying the logical volume groups to copy from and to, respectively. If no target VG is passed, WereSync will use the VG SOURCE-copy. If the target does not exist, WereSync will create it.

No Volume Groups are copied

–bootloader BOOTLOADER


The plugin to use to install the bootloader. Such plugins can be found at the bottom of the help message.

The “uuid_copy” plugin.



Makes WereSync increase output and include more minor details.

Only Warnings, more serious issues, and basic info are printed.



Causes a huge amount of output, useful for debugging the program. Usually not needed for casual use.

Only Warnings, more serious issues, and basic info are printed.