ocs-onthefly(8)                Clonezilla Manual               ocs-onthefly(8)

NAME
       ocs-onthefly - Clonezilla: on-the-fly disk or partition(s) cloning

SYNOPSIS
       ocs-onthefly [OPTION]

DESCRIPTION
       ocs-onthefly is used for "disk to disk" or "partition to partition"
       clone on-the-fly, either locally or over the network.

OPTIONS
       -b, -batch, --batch, --batch-mode
              Run program in batch mode (dangerous!), i.e., without any prompt
              or wait for confirmation.

       -cmf, --chk-chksum-for-files-in-dev
              Do the files checksum inspection for cloned files in destination
              devices.

       -d, --destination, --target DEV
              Specify the target device as DEV (e.g., /dev/sdb or sdb).

       -e1, --change-geometry NTFS-BOOT-PARTITION
              Force to change the CHS (cylinders, heads, sectors) value of
              NTFS boot partition after cloning. NTFS-BOOT-PARTITION can be
              "auto" or a device name.

       -e2, --load-geometry-from-edd
              Force to use the CHS from EDD (Enhanced Disk Device) when
              creating partition table by sfdisk.

       -r, --resize-partition
              Resize the file system size to fit the partition size in the
              destination disk.

       -f, --source DEV
              Specify the source device as DEV (e.g., /dev/sda or sda).

       -g, --grub-install GRUB_PARTITION
              Install grub in the MBR. GRUB_PARTITION can be "auto" or a
              device name.

       --net-filter PROGRAM
              Use the PROGRAM (gzip, lzop, bzip2, xz, lz4, zstd, cat) before
              sending partition data to netcat/nuttcp (only in network clone
              mode). Default is zstd.

       -nogui, --nogui
              Do not show GUI (TUI), use text only.

       -rescue, --rescue
              Turn on rescue mode, i.e., try to skip bad sectors.

       -rvd, --rvd
              Remove the NTFS volume dirty flag in source NTFS file system
              before cloning it.

       -irhr, --irhr
              Skip removing the Linux udev hardware records on the restored
              GNU/Linux.

       -ius, --ius
              Skip updating syslinux-related files on the restored GNU/Linux.

       -iui, --iui
              Skip updating initramfs file(s) on the restored GNU/Linux.

       -icds, --ignore-chk-dsk-size-pt
              Skip checking destination disk size before creating the
              partition table.

       -iefi, --ignore-update-efi-nvram
              Skip updating boot entries in EFI NVRAM after cloning.

       -k, --no-sfdisk
              Do NOT create partition table in boot sector in target machine.

       -k0    Create partition table based on the partition table from the
              source (default).

       -k1    Create partition table in the target disk proportionally.

       -k2    Enter command line prompt to create partition table manually
              before cloning.

       -j2, --clone-hidden-data
              Use dd to clone the image of the data between MBR (1st sector)
              and 1st partition.

       -m, --no-boot-loader-clone
              Do NOT clone boot loader.

       -o, --load-geometry
              Force to use the saved CHS (cylinders, heads, sectors) when
              using sfdisk.

       -q1, --force-to-use-dd
              Force to use sector-by-sector copy (slow but works for all
              filesystems).

       -po, --port PORT
              Specify the netcat port (only in network clone mode).

       -p, -pa, --postaction ACTION
              Action when cloning finishes: [choose|poweroff|reboot|true|CMD].

       -a, --server
              Specify the running machine is the network clone server.

       -s, --source-IP IP
              Specify the source IP address (used in target client machine).

       -t, --no-restore-mbr
              Do NOT restore the MBR.

       -t1, --restore-raw-mbr
              Restore the prebuilt bootloader from syslinux (For Windows
              only).

       -t2, --no-restore-ebr
              Do NOT restore the EBR.

       -v, --verbose
              Prints verbose information.

       -np, --net-pipe PROGRAM
              Use PROGRAM as network pipe program. Available: netcat, nuttcp.

       -x, --interactive
              Interactive mode.

       -bm, --beginner-mode
              Run in beginner mode (shortcut for "-um beginner").

       -em, --expert-mode
              Run in expert mode (shortcut for "-um expert").

       -um, --user-mode [beginner|expert]
              Specify the user mode.

       -edio, --enable-direct-io
              Enable the direct IO mode of Partclone for NVMe SSD.

EXAMPLES
       1. To clone local sda to local sdb:

              ocs-onthefly -f sda -d sdb

       2. To clone sda from machine A (IP 192.168.100.1) to sda on machine B
       via network:

       On machine A:

              ocs-onthefly -a -f sda

       On machine B:

              ocs-onthefly -s 192.168.100.1 -d sda

FILES
       /etc/drbl/drbl-ocs.conf
              The configuration file for Clonezilla.

SEE ALSO
       ocs-sr(8), drbl-ocs(8)

AUTHORS
       Steven Shiau <steven _at_ clonezilla org>

Clonezilla                        2026-05-03                   ocs-onthefly(8)