dd

dd

The dd program reads from a specified input file (stdin is the default), performs whatever conversions you specify, and writes the result to a specified output file (stdout is the default). It is not specifically a backup tool, but has many extremely useful features, including the ability to:

skip specific blocks in an archive
skip blocks of output
specify input and output block size
copy a specific number of blocks
perform various data conversions such as byte swapping

Refer to the dd(1M) reference page for details on the use of the dd command.