Command: copy

Copy: -c [src] [dest] [len]

Copies data from the source inserting it at the destination

hexed -c 100 200 20 file

This will copy 32 bytes from 0x100 to 0x200 moving everything at 0x200 up by 32 bytes.

Copy Overwrite: -co [src] [dest] [len]

Copies data from the source overwriting the destination

hexed -co 100 200 20 file

Copy 32 bytes from 0x100 to 0x200 overwriting the original data.