---
name: "ocs-onthefly"
section: "8"
platform: "linux"
package: "clonezilla"
version: "5.19.7-1"
release: "Arch Linux 2026-11-01"
platforms: ["linux"]
url: "https://new.carta.tech/ocs-onthefly"
---

# ocs-onthefly(8)

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

## 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)](/ocs-sr/8.md), **drbl-ocs**(8)

## AUTHORS

Steven Shiau \<steven \_at\_ clonezilla org\>