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dd

Introduction​

This cheat sheet provides a quick reference for some common dd (data duplication) commands and concepts. dd is a versatile command-line utility used for copying and converting files, as well as for creating disk images on Unix-like operating systems.

dd Concepts​

Input and Output​

dd uses input and output options to specify the source and destination of data.

  • Input file (source):

    if=input_file

  • Output file (destination):

    of=output_file

Block Size and Count​

You can specify the block size and count to control how data is read and written.

  • Block size (bytes):

    bs=block_size

  • Block count (number of blocks):

    count=block_count

Skip and Seek​

dd allows you to skip input data or seek to a specific position in the input data.

  • Skip N blocks from the input:

    skip=N

  • Seek N blocks from the beginning of the output:

    seek=N

Status​

dd can display progress information, including the number of records in and out.

  • Show progress (send a signal to dd process):
    status=progress

Conversions​

You can use conv to perform conversions on the data during copying.

  • Convert ASCII to EBCDIC:

    conv=ebcdic

  • Convert EBCDIC to ASCII:

    conv=ascii

Disk Images​

dd is commonly used to create disk images.

  • Create a disk image of a device:
    dd if=/dev/source_device of=disk_image.img bs=4M

dd Command-Line​

  • Copy data from one file to another:

    dd if=input_file of=output_file bs=block_size count=block_count

  • Create a disk image from a device:

    dd if=/dev/source_device of=disk_image.img bs=block_size

  • Show progress while copying:

    dd if=input_file of=output_file bs=block_size count=block_count status=progress

  • Convert file format from ASCII to EBCDIC:

    dd if=input_file of=output_file conv=ebcdic

  • Securely erase a disk with random data:

    dd if=/dev/urandom of=/dev/target_device bs=4M status=progress

Conclusion​

This cheat sheet covers some common dd (Data Duplication) commands and concepts. dd is a powerful command-line utility for copying, converting, and creating disk images; refer to the official dd documentation for more in-depth information and advanced usage.